Novak Conversions Jeep Wrangler TJ engine mounts

Working through final wiring issues on my build and I'm stumped

Gormy

Member
Original poster
Joined
Nov 8, 2023
Messages
76
Location
Wilmington, NC
Hello all,

I am wrapping up my 6+ month build. I bought a 1999 TJ with a bad tub and frame, but good interior, body parts and drivetrain (only 86k miles). Most of the wiring worked on the old Jeep before I swapped everything to a new frame and tub, so my guess is I did something wrong. But I'm stumped on what I did. I have two primary issues: it only starts if I jump the starter from the battery, and I have a NO BUS issue on the dash.

No start issue: If I turn the key to on, the fuel pump kicks in. If I turn it to run and jump the starter, it fires right up and runs perfect. I even took it for two short drives around my neighborhood. It has new plugs, wires, battery, battery clamps, and a new starter. I ordered a new ignition switch and actuator pin. Ignition switch is delayed at customs so I don't know when it will be here. I bought those on the recommendation of others on here, but I don't think it's going to be the problem. When I turn the key to start the Jeep, it clicks in the fuse panel behind the glove box. So it's clearly sending a signal through there. When I test for power at the starter wire, I get nothing. So I'm guessing the connection is bad/broken somewhere between the ignition and starter. I'm just not great at reading wiring diagrams to track this down, so I'm hoping someone can help me and put it in simple terms. I've checked all the fuses that could be the cause and they all work. I don't want to buy a relay yet unless there's a good chance that is it. I tried watching videos on jumping the relay with a wire to see if it's bad, but it didn't make complete sense to me as to what I was supposed to do. Where do I go from here?

NO BUS issue: I have disconnected, inspected, cleaned, and reconnected every wire harness I can find, including the two that plug into the gauge cluster. I can't find what's wrong. All the lights on the outside of the Jeep are new and all work. Radio works. HVAC works. Fuel pump works. Everything electronic is working, so I don't know what is left that isn't connected. I replaced the coolant temp sensor because it was snapped and had a broken wire. I disconnected and inspected the other 5v connectors (throttle position sensor, crank position sensor, cam position sensor, and so on), and I saw no issues with them. There was no NO BUS issue on the Jeep when I bought it, so I definitely think it's something I did wrong or forgot to do. All grounds are hooked up inside including the two to the speaker mounts, back of the radio, and to the kick panels on each side. The main battery wire harness under the hood is grounded to the firewall, engine is grounded to the frame, and the ribbon from the block is attached to the hood. What else is left to check?

Are these two issues related? I am at the very end of this build and these are going to keep me from being able to drive it everywhere. I need to repair, paint and remount the roll bar and fix these wiring issues, and it'll be driving. I'm getting very frustrated trying to track these two issues down.
 
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Current picture versus what I started with. It has been a full, from-scratch, build. New frame, body, paint, lift, axles, all suspension and steering, clutch, pressure plate and bearings, engine tune up, all fluids, bumpers, everything! I just want to start taking it to the beach and I’m stuck chasing these issues.

IMG_6588.jpeg


IMG_4452.jpeg
 
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How thoroughly did you go over the harness before reinstallation? I used my frame and tub swap as an opportunity to deloom and inspect a little t of my wiring.

I'd double check you have your harness connectors in the right spots on the big block under the dash and they're fully seated and corrosion free.

And look up the ground chart and verify every ground is connected. The drivers side kick panel gets missed a lot. Same with the headlights.

-Mac
 
How thoroughly did you go over the harness before reinstallation? I used my frame and tub swap as an opportunity to deloom and inspect a little t of my wiring.

I'd double check you have your harness connectors in the right spots on the big block under the dash and they're fully seated and corrosion free.

And look up the ground chart and verify every ground is connected. The drivers side kick panel gets missed a lot. Same with the headlights.

-Mac

I didn't go over the harness super closely because everything worked. Obviously I checked for any obvious signs of damage or breaks, but I didn't take all the looms off. I checked the big block under the dash last night. They're all color coded and the harnesses can really only plug in one way with how they're wrapped and the length of each harness. But I took all of them out, checked for corrosion, and plugged them back in. Still have both issues. I looked up ground charts and I have every ground that I can find in the charts attached as they should be. The headlights work fine. I rewired the connectors when I installed new lights because the old ones were gone and the previous owner bypassed the connectors and put the wires directly to the light. High beam, low beam, parking lights, tail lights, brake lights, turn signals and emergency flashers all work as they should.

I can't find any ground issue anywhere.
 
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Check the wiring to your ignition actuator.

I have to the best I can/understand without more input from others. As I mentioned in my post, if I try and start the Jeep, there is a clicking from behind the glovebox. That tells me the wiring is intact. I have unplugged and plugged it back in 20+ times, wiggled it around to see if it has a loose connection, and anything else I can think of. I still can't get it to turn over with the key. Once the new parts come in I will swap them in, but I really don't think that's going to be the issue.
 
Check the battery connection. I swear they can seem right and they’re not and it can make all the difference.

After that try the actuator and ignition switch.
 
Check the battery connection. I swear they can seem right and they’re not and it can make all the difference.

After that try the actuator and ignition switch.

Brand new battery and connectors. Everything else electronic works on the Jeep.

The ignition switch is on the way but delayed getting here. But as I posted above, I don't know that it will be the issue since I can still hear the key clicking something in the fuse panel, which tells me it is getting a signal from the switch.
 
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Yeah I'd stand down until you get that switch. Don't want to cause the next issue.

Jump it and drive it to the beach and celebrate your achievements.

-Mac
 
Current picture versus what I started with. It has been a full, from-scratch, build. New frame, body, paint, lift, axles, all suspension and steering, clutch, pressure plate and bearings, engine tune up, all fluids, bumpers, everything! I just want to start taking it to the beach and I’m stuck chasing these issues.

View attachment 535234

View attachment 535235

Bypass the clutch safety switch by installing the fuse in the fuse block behind the dash and see what happens.
 
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I should have mentioned that. I did that as one of the first steps and it doesn't change anything.

Pull the column bezel, ignition lock, ignition actuator and turn the ignition switch itself with a screw driver to see if the actuator is the problem and not the actual ignition switch itself. Alternately, you can just remove the switch from the left side and test it by turning it manually.
 
Pull the column bezel, ignition lock, ignition actuator and turn the ignition switch itself with a screw driver to see if the actuator is the problem and not the actual ignition switch itself. Alternately, you can just remove the switch from the left side and test it by turning it manually.

I have tried so many things that I forgot to list them all. I tried this too from seeing it in a different forum. I took the ignition switch off and removed the actuator. I can turn the switch with a screwdriver and nothing changes.
 
We get a NO BUS when there are certain fuses blown in the PDC. The last one was on the output from the IOD fuse and relay circuit that I blew hooking up a feed from a courtesy light. As soon as I blew it, we got the NO BUS. Check every fuse with a test light. Check both pins with the probe.
 
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We get a NO BUS when there are certain fuses blown in the PDC. The last one was on the output from the IOD fuse and relay circuit that I blew hooking up a feed from a courtesy light. As soon as I blew it, we got the NO BUS. Check every fuse with a test light. Check both pins with the probe.

I will run back through tonight and recheck every fuse in the PDC.
 
Please fill out your profile. All I know from your post is you have a 99 TJ. If your profile was filled out, I could quickly determine which engine and which transmission you have, and it would be easier to help. Fortunately, I recall your previous posts about a manual transmission/clutch problem. Here's the starting system wiring diagram:

1718720899983.png


If you look at that, the relay is the key component. A relay is a way to switch a high-current system with a low-current switch (so the switch doesn't melt). The solenoid on the starter draws enough current to require a relay. The relay is a mechanical device, and the schematic above helps understand how it works. On the left side of the schematic is the coil of the relay, part of an electro-magnet. It's shown by the zig-zaggy line and the rectangle with a slash in it. On a manual transmission TJ, the BR/LB wire (BRown with a Light Blue stripe) grounds one side of the relay's coil all the time. Energization of the relay is controlled by the positive side only.

When you turn the key to the start position, battery positive is connected through contact #1 in the ignition switch schematic (upper left corner above) via the YL wire (YeLlow), through either Fuse 20 (the "clutch bypass fuse", which is not installed by the factory) or through the clutch pedal switch once you depress the clutch. Notice that Fuse 20 and the clutch pedal switch are in parallel circuits, both using YL/RD wires (YeLlow with a ReD stripe). That means that the starter relay coil will be energized anytime the ignition switch is rotated to the start position, and either or both the clutch pedal switch is engaged by pressing the clutch pedal or Fuse 20 is inserted. With Fuse 20 in place, you can start the TJ in gear, which is helpful if you are off-road on a hill. It's not installed by default for safety reasons.

Now, once the coil on the relay engages, it's magnetic field moves the switching mechanism. That's the dashed line running left-right inside the relay schematic above. When the mechanism moves, the switch on the right side of the relay schematic changes position, closing the circuit that supplies 12V to the starter solenoid. The starter solenoid performs two actions. First, it moves the drive gear on the starter outwards to engage the ring gear on the flywheel. Second, it connects the starter to battery 12V so that it starts spinning.

How the switch on the right side of the solenoid works is pretty straight-forward, if you study the schematic some more. Fuse 2 supplies 12V to the stationary side of the relay's switch via the PK/BK wire (Pink with a Black stripe). When the relay's switch is closed by the relay's coil energizing, that 12V goes through the switch to the BR wire (Brown) on the other side. That Brown wire goes through harness connector #104 ("C104") and on to the starter solenoid, which fires up your TJ.

To check your starter system, I'd suggest checking for all these conditions when the key is in the start position (you'll probably need a helper) and with the starter relay installed (you may have to get creative to get readings on your meter with the relay in place - perhaps remove the PDC and turn it upside down to touch the terminals):
  1. 12V on the YL/RD wire's terminal at the starter relay (if no, check the ignition switch and harness)
  2. Continuity with Batt - at the BR/LB wire's terminal at the starter relay (if no, check the harness)
  3. 12V on the PK/BK wire's terminal at the starter relay (if no, check Fuse 2 and the harness)
  4. 12V on the BR wire's terminal at the starter relay (if no, check the relay)
  5. 12V on the BR wire's terminal at the starter solenoid terminal on the starter (if no, check the harness)
You should also have 12V at the starter's largest terminal at all times (it's connected to the battery). If all of this checks out, it's likely a battery connection or ground issue. Never assume that those are good from just looking at them. It takes a near-perfect connection to transfer a couple-hundred amps when the starter motor is running. That's a lot of energy!

The manual has a helpful section on how relay terminals are numbered, but it's not exactly easy to understand. First, rather than saying what type of relay was used, they just show examples of two different configurations. Secondly, on one of them, they show the terminal labels from the perspective of looking at the relay socket in the PDC, but on the other it's shown from the perspective of looking at the relay, with the terminals pointing up. Therefore, one of them is a mirror image of the other. Here are both of them, and I've put the wire colors on it, so that you can relate it to the schematic. They are both edited so that the terminal arrangement is from the perspective of looking down at the relay socket in the PDC, as though the relay is not there. The one on the right is a mirror-image, so I've re-labelled terminals 85 and 86. Also, remember that if you turn the PDC upside down to probe the terminals, they will then be a mirror image of what's shown below. Note that the normally-closed terminal (87A) is not used for a starter relay, so that terminal slot is likely empty in the PDC.

1718723553629.png


Also, you mentioned that you couldn't figure out how to jumper the starter relay. It's pretty easy, and it might be the first thing to try. Remove the starter relay, and use a paper clip to carefully connect terminals 87 (BR) and 30 (PK/BK). What I mean by carefully is that the paper clip will become energized with 12V as soon as you touch terminal 30 (PK/BK). If it touches any metal, you'll get fireworks. Jumpering the relay terminals will simulate the starter relay energizing and closing the switch. If that starts the TJ, your relay is bad - either the coil is burned out, or the switch mechanism is "finky". Good luck. Post back with your discoveries.

Also, there don't appear to be any computers involved in the starter circuit, so I don't think your "NO BUS" problem is causing the starter problem. I am also unfamiliar with that error. I'm assuming it's what is displayed on the dash, where the odometer normally is?
 
Please fill out your profile. All I know from your post is you have a 99 TJ. If your profile was filled out, I could quickly determine which engine and which transmission you have, and it would be easier to help. Fortunately, I recall your previous posts about a manual transmission/clutch problem. Here's the starting system wiring diagram:

View attachment 535371

If you look at that, the relay is the key component. A relay is a way to switch a high-current system with a low-current switch (so the switch doesn't melt). The solenoid on the starter draws enough current to require a relay. The relay is a mechanical device, and the schematic above helps understand how it works. On the left side of the schematic is the coil of the relay, part of an electro-magnet. It's shown by the zig-zaggy line and the rectangle with a slash in it. On a manual transmission TJ, the BR/LB wire (BRown with a Light Blue stripe) grounds one side of the relay's coil all the time. Energization of the relay is controlled by the positive side only.

When you turn the key to the start position, battery positive is connected through contact #1 in the ignition switch schematic (upper left corner above) via the YL wire (YeLlow), through either Fuse 20 (the "clutch bypass fuse", which is not installed by the factory) or through the clutch pedal switch once you depress the clutch. Notice that Fuse 20 and the clutch pedal switch are in parallel circuits, both using YL/RD wires (YeLlow with a ReD stripe). That means that the starter relay coil will be energized anytime the ignition switch is rotated to the start position, and either or both the clutch pedal switch is engaged by pressing the clutch pedal or Fuse 20 is inserted. With Fuse 20 in place, you can start the TJ in gear, which is helpful if you are off-road on a hill. It's not installed by default for safety reasons.

Now, once the coil on the relay engages, it's magnetic field moves the switching mechanism. That's the dashed line running left-right inside the relay schematic above. When the mechanism moves, the switch on the right side of the relay schematic changes position, closing the circuit that supplies 12V to the starter solenoid. The starter solenoid performs two actions. First, it moves the drive gear on the starter outwards to engage the ring gear on the flywheel. Second, it connects the starter to battery 12V so that it starts spinning.

How the switch on the right side of the solenoid works is pretty straight-forward, if you study the schematic some more. Fuse 2 supplies 12V to the stationary side of the relay's switch via the PK/BK wire (Pink with a Black stripe). When the relay's switch is closed by the relay's coil energizing, that 12V goes through the switch to the BR wire (Brown) on the other side. That Brown wire goes through harness connector #104 ("C104") and on to the starter solenoid, which fires up your TJ.

To check your starter system, I'd suggest checking for all these conditions when the key is in the start position (you'll probably need a helper) and with the starter relay installed (you may have to get creative to get readings on your meter with the relay in place - perhaps remove the PDC and turn it upside down to touch the terminals):
  1. 12V on the YL/RD wire's terminal at the starter relay (if no, check the ignition switch and harness)
  2. Continuity with Batt - at the BR/LB wire's terminal at the starter relay (if no, check the harness)
  3. 12V on the PK/BK wire's terminal at the starter relay (if no, check Fuse 2 and the harness)
  4. 12V on the BR wire's terminal at the starter relay (if no, check the relay)
  5. 12V on the BR wire's terminal at the starter solenoid terminal on the starter (if no, check the harness)
You should also have 12V at the starter's largest terminal at all times (it's connected to the battery). If all of this checks out, it's likely a battery connection or ground issue. Never assume that those are good from just looking at them. It takes a near-perfect connection to transfer a couple-hundred amps when the starter motor is running. That's a lot of energy!

The manual has a helpful section on how relay terminals are numbered, but it's not exactly easy to understand. First, rather than saying what type of relay was used, they just show examples of two different configurations. Secondly, on one of them, they show the terminal labels from the perspective of looking at the relay socket in the PDC, but on the other it's shown from the perspective of looking at the relay, with the terminals pointing up. Therefore, one of them is a mirror image of the other. Here are both of them, and I've put the wire colors on it, so that you can relate it to the schematic. They are both edited so that the terminal arrangement is from the perspective of looking down at the relay socket in the PDC, as though the relay is not there. The one on the right is a mirror-image, so I've re-labelled terminals 85 and 86. Also, remember that if you turn the PDC upside down to probe the terminals, they will then be a mirror image of what's shown below. Note that the normally-closed terminal (87A) is not used for a starter relay, so that terminal slot is likely empty in the PDC.

View attachment 535378

Also, you mentioned that you couldn't figure out how to jumper the starter relay. It's pretty easy, and it might be the first thing to try. Remove the starter relay, and use a paper clip to carefully connect terminals 87 (BR) and 30 (PK/BK). What I mean by carefully is that the paper clip will become energized with 12V as soon as you touch terminal 30 (PK/BK). If it touches any metal, you'll get fireworks. Jumpering the relay terminals will simulate the starter relay energizing and closing the switch. If that starts the TJ, your relay is bad - either the coil is burned out, or the switch mechanism is "finky". Good luck. Post back with your discoveries.

Also, there don't appear to be any computers involved in the starter circuit, so I don't think your "NO BUS" problem is causing the starter problem. I am also unfamiliar with that error. I'm assuming it's what is displayed on the dash, where the odometer normally is?

Sab,

I can't thank you enough for spending the time to write this up. This is exactly what I needed. I felt like I am going crazy trying to search through every forum post about a no crank, no start issue. I know wiring well enough to wire in headlights, radios, and things like that. But getting into this level is a little beyond my comfort. I was able to mechanically build this Jeep from scratch, and that's where my experience lies. I also added my Jeep to my profile; thank you for pointing that out, and apologies for not having it done already.

I do not have a helper here, so it's going to be difficult to try all your steps you listed out for checking the wiring voltage. So for now I skipped to jumping the starter relay. With the Jeep off, the key not on run or start, and jumping 87 to 30 with a paperclip, it cranks over right away. Does this mean that I go pick up a relay now to see if that solves it?

And you are correct on the NO BUS issue. That is what shows up on the dash where the odometer is. It means the gauge cluster isn't getting clear communication from and of the onboard computers. I didn't think it would be related to the starting issue, but I was hopeful that figuring out one issue would fix both!
 
Current picture versus what I started with. It has been a full, from-scratch, build. New frame, body, paint, lift, axles, all suspension and steering, clutch, pressure plate and bearings, engine tune up, all fluids, bumpers, everything! I just want to start taking it to the beach and I’m stuck chasing these issues.

Please fill out your profile. All I know from your post is you have a 99 TJ. If your profile was filled out, I could quickly determine which engine and which transmission you have, and it would be easier to help. Fortunately, I recall your previous posts about a manual transmission/clutch problem. Here's the starting system wiring diagram:

View attachment 535371

If you look at that, the relay is the key component. A relay is a way to switch a high-current system with a low-current switch (so the switch doesn't melt). The solenoid on the starter draws enough current to require a relay. The relay is a mechanical device, and the schematic above helps understand how it works. On the left side of the schematic is the coil of the relay, part of an electro-magnet. It's shown by the zig-zaggy line and the rectangle with a slash in it. On a manual transmission TJ, the BR/LB wire (BRown with a Light Blue stripe) grounds one side of the relay's coil all the time. Energization of the relay is controlled by the positive side only.

When you turn the key to the start position, battery positive is connected through contact #1 in the ignition switch schematic (upper left corner above) via the YL wire (YeLlow), through either Fuse 20 (the "clutch bypass fuse", which is not installed by the factory) or through the clutch pedal switch once you depress the clutch. Notice that Fuse 20 and the clutch pedal switch are in parallel circuits, both using YL/RD wires (YeLlow with a ReD stripe). That means that the starter relay coil will be energized anytime the ignition switch is rotated to the start position, and either or both the clutch pedal switch is engaged by pressing the clutch pedal or Fuse 20 is inserted. With Fuse 20 in place, you can start the TJ in gear, which is helpful if you are off-road on a hill. It's not installed by default for safety reasons.

Now, once the coil on the relay engages, it's magnetic field moves the switching mechanism. That's the dashed line running left-right inside the relay schematic above. When the mechanism moves, the switch on the right side of the relay schematic changes position, closing the circuit that supplies 12V to the starter solenoid. The starter solenoid performs two actions. First, it moves the drive gear on the starter outwards to engage the ring gear on the flywheel. Second, it connects the starter to battery 12V so that it starts spinning.

How the switch on the right side of the solenoid works is pretty straight-forward, if you study the schematic some more. Fuse 2 supplies 12V to the stationary side of the relay's switch via the PK/BK wire (Pink with a Black stripe). When the relay's switch is closed by the relay's coil energizing, that 12V goes through the switch to the BR wire (Brown) on the other side. That Brown wire goes through harness connector #104 ("C104") and on to the starter solenoid, which fires up your TJ.

To check your starter system, I'd suggest checking for all these conditions when the key is in the start position (you'll probably need a helper) and with the starter relay installed (you may have to get creative to get readings on your meter with the relay in place - perhaps remove the PDC and turn it upside down to touch the terminals):
  1. 12V on the YL/RD wire's terminal at the starter relay (if no, check the ignition switch and harness)
  2. Continuity with Batt - at the BR/LB wire's terminal at the starter relay (if no, check the harness)
  3. 12V on the PK/BK wire's terminal at the starter relay (if no, check Fuse 2 and the harness)
  4. 12V on the BR wire's terminal at the starter relay (if no, check the relay)
  5. 12V on the BR wire's terminal at the starter solenoid terminal on the starter (if no, check the harness)
You should also have 12V at the starter's largest terminal at all times (it's connected to the battery). If all of this checks out, it's likely a battery connection or ground issue. Never assume that those are good from just looking at them. It takes a near-perfect connection to transfer a couple-hundred amps when the starter motor is running. That's a lot of energy!

The manual has a helpful section on how relay terminals are numbered, but it's not exactly easy to understand. First, rather than saying what type of relay was used, they just show examples of two different configurations. Secondly, on one of them, they show the terminal labels from the perspective of looking at the relay socket in the PDC, but on the other it's shown from the perspective of looking at the relay, with the terminals pointing up. Therefore, one of them is a mirror image of the other. Here are both of them, and I've put the wire colors on it, so that you can relate it to the schematic. They are both edited so that the terminal arrangement is from the perspective of looking down at the relay socket in the PDC, as though the relay is not there. The one on the right is a mirror-image, so I've re-labelled terminals 85 and 86. Also, remember that if you turn the PDC upside down to probe the terminals, they will then be a mirror image of what's shown below. Note that the normally-closed terminal (87A) is not used for a starter relay, so that terminal slot is likely empty in the PDC.

View attachment 535378

Also, you mentioned that you couldn't figure out how to jumper the starter relay. It's pretty easy, and it might be the first thing to try. Remove the starter relay, and use a paper clip to carefully connect terminals 87 (BR) and 30 (PK/BK). What I mean by carefully is that the paper clip will become energized with 12V as soon as you touch terminal 30 (PK/BK). If it touches any metal, you'll get fireworks. Jumpering the relay terminals will simulate the starter relay energizing and closing the switch. If that starts the TJ, your relay is bad - either the coil is burned out, or the switch mechanism is "finky". Good luck. Post back with your discoveries.

Also, there don't appear to be any computers involved in the starter circuit, so I don't think your "NO BUS" problem is causing the starter problem. I am also unfamiliar with that error. I'm assuming it's what is displayed on the dash, where the odometer normally is?

I figured it out from his second post once I quit skimming and started reading. ;)
 
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Novak Conversions Jeep Wrangler TJ engine mounts