Few things worse than intermittent electrical issues

[MikekiM]

Jeep is sitting for the past few days.

I've been dealing with an intermittent no-start issue.

First happened right after the transmission swap so thinking the shop might have funked something at the starter. Thought it was just a cold weather issue so did a warranty replacement on the battery and it happened two more times. It will be fine for days and turning the key yields just a single click. Lights are dim, horn is anemic. Voltage will be down around 12. Jump start will get it going after a bit and then it runs and starts fine, until it doesn't.

Battery checks fine. CCA exceed the battery rating. Alternator is fine. Overnight draw is about 60 milliamps.. A little higher than ideal but I have two LED accessories (a clock and a voltage gauge) that are on full time. All cable seem to be in good order.. I have the Big 7 kit.

Haven't changed anything in the electric system. Only thing I can pinpoint is the partial removal of the starter to swap the transmission.

We've had some great winter camping weather but I have zero confidence to be miles from the nearest anything...

 

[KennethS]

In my experience, that single click means a poor connection somewhere. Enough current will initially pass to energize the relay / solenoid, then the circuit opens and stops current flow.

Might need to drop the starter and ensure the mating surfaces are clean so there’s good electrical contact.

Same for all the cable connections - also be aware the battery cable can look good at the terminal end, but there can be corrosion under the insulation.

 

[Link]

Pull the fuses for the most likely power drains. If the overnight drain stops, that’s where your problem is. Now you just have to narrow down to the specifics.

It’s always possible there is something wrong in the starter but I’m inclined to think it’s unlikely. I’m not very familiar with the electric components of the auto transmission but I’d tend to suspect the new transmission. I’d pull all fuses related to the transmission and see if the drains continue.

 

[macleanflood]

I'd start with grounds. Nut and bolt check your cable kit. I melted my fuse holder... cable came loose.

-Mac

 

[MikekiM]

In my experience, that single click means a poor connection somewhere. Enough current will initially pass to energize the relay / solenoid, then the circuit opens and stops current flow.

Might need to drop the starter and ensure the mating surfaces are clean so there’s good electrical contact.

Same for all the cable connections - also be aware the battery cable can look good at the terminal end, but there can be corrosion under the insulation.

I'd start with grounds. Nut and bolt check your cable kit. I melted my fuse holder... cable came loose.

-Mac

I am in agreement with both of you ^^^

The battery connections are solid. As are the grounds to firewall and block. I am betting on either a dislodged connection at the starter or a bad starter entirely.

The shop that did the transmission swap is on the hook for this. Bringing it back to them early this week. The first time it happened was a few days after bringing it home after the swap.

After doing the Big7 kit I had a loose ground at the firewall and the telltale was erratic alternator output.

Pull the fuses for the most likely power drains. If the overnight drain stops, that’s where your problem is. Now you just have to narrow down to the specifics.

It’s always possible there is something wrong in the starter but I’m inclined to think it’s unlikely. I’m not very familiar with the electric components of the auto transmission but I’d tend to suspect the new transmission. I’d pull all fuses related to the transmission and see if the drains continue.

With the overnight draw being almost perfect (50 milliamps would be perfect) I don't think it is a power drain.

I swapped an NV3550 out for a Novak AX15.

 

[B1Toad]

Where are you reading the 12 volts when you get the dim lights and anemic horn? From an in cabin voltmeter or directly on the battery posts (not the clamps) with a DVM? This could be a big help in locating where the the problem is.

 

[mkc1962]

Have you checked the condition of your relays/Sockets? My 2000 had all sorts of corrosion in just about all the sockets where all the relays were plugged in. If the starter relay is compromised, the solenoid aint pulling in....corrosion gremlins can come and go. I have disassembled and cleaned, then dielectric greased just about all the plugs/sockets/etc on my 2000 as I am bringing it back to life...I dont think I have ever found as much connector corrosion on a vehicle ever.

 

[MikekiM]

Left it sitting since Friday. Started right up this afternoon

I am ruling out parasitic draw and cold temps killing the battery.

 

[Mac57]

I know you are relating this issue to the recent trans swap, but perhaps there is something else coincidently happening. If you had this issue pop up, without the trans swap, what would you be checking? You have done some of that already, grounds, battery, parasitic draw. Have you considered an ignition switch issue, such as the common broken actuator pin? Or perhaps the wiring to the starter, or the starter itself?

 

[macleanflood]

I've got an Optima Yellow Top. AGM deep cycle battery. My TJ charges around 13.8 to 14 volts and it's not quite enough to be optimal charging voltage for my battery. As such it never quite fully charged and doesn't really function much like a deep cycle for voltage dependent things...my fridge auto shuts off at 11.7 and that's about 15 minutes of run time without the Jeep running. My solution is pretty much keep the Jeep on a trickle charger. Debating whether or not I spend the money on HP Tuners and reprogramming the charge voltage to something like 14.6.

I don't know if this is your problem or a solution but I figured it was worth mentioning.

-Mac

 

[MikekiM]

I know you are relating this issue to the recent trans swap, but perhaps there is something else coincidently happening. If you had this issue pop up, without the trans swap, what would you be checking? You have done some of that already, grounds, battery, parasitic draw. Have you considered an ignition switch issue, such as the common broken actuator pin? Or perhaps the wiring to the starter, or the starter itself?

Not the ignition switch. I am leaning towards the starter.
I left it a shop on Friday that specialized in mystery electrical issues.. they checked everything they could and said starter. It's going back to the shop that did the swap.

I've got an Optima Yellow Top. AGM deep cycle battery. My TJ charges around 13.8 to 14 volts and it's not quite enough to be optimal charging voltage for my battery. As such it never quite fully charged and doesn't really function much like a deep cycle for voltage dependent things...my fridge auto shuts off at 11.7 and that's about 15 minutes of run time without the Jeep running. My solution is pretty much keep the Jeep on a trickle charger. Debating whether or not I spend the money on HP Tuners and reprogramming the charge voltage to something like 14.6.

I don't know if this is your problem or a solution but I figured it was worth mentioning.

-Mac

I have the same battery. My TJ charges 14 - 14.4 v.
Battery is newly replaced in Dec '23. Build date is July '23.
No accessories are left on and given it has sat since Friday with temps well below freezing and started up this morning, I am ruling out parasitic draw or defective battery.

 

[MikekiM]

Where are you reading the 12 volts when you get the dim lights and anemic horn? From an in cabin voltmeter or directly on the battery posts (not the clamps) with a DVM? This could be a big help in locating where the the problem is.

Both... an interior voltage meter and at the batter posts. Battery went through multiple tests. I don't believe it's the battery.

 

[JeepNStein]

Jeep is sitting for the past few days.

I've been dealing with an intermittent no-start issue.

First happened right after the transmission swap so thinking the shop might have funked something at the starter. Thought it was just a cold weather issue so did a warranty replacement on the battery and it happened two more times. It will be fine for days and turning the key yields just a single click. Lights are dim, horn is anemic. Voltage will be down around 12. Jump start will get it going after a bit and then it runs and starts fine, until it doesn't.

Battery checks fine. CCA exceed the battery rating. Alternator is fine. Overnight draw is about 60 milliamps.. A little higher than ideal but I have two LED accessories (a clock and a voltage gauge) that are on full time. All cable seem to be in good order.. I have the Big 7 kit.

Haven't changed anything in the electric system. Only thing I can pinpoint is the partial removal of the starter to swap the transmission.

We've had some great winter camping weather but I have zero confidence to be miles from the nearest anything...

I have been experiencing nearly the same. I cleaned the ground at the engine and cleaned the battery terminals. Still issues. Check wires for corrosion. Tested starter relay... all good.. Turns out it was the solenoid in the starter. Replaced it with a PA Performance 1699 starter and it is fixed. If you have help, do the tests that are in the FSM.

 

[MikekiM]

I have been experiencing nearly the same. I cleaned the ground at the engine and cleaned the battery terminals. Still issues. Check wires for corrosion. Tested starter relay... all good.. Turns out it was the solenoid in the starter. Replaced it with a PA Performance 1699 starter and it is fixed. If you have help, do the tests that are in the FSM.

The starter was replaced about 18 mos ago when I did the Big 7 wires. Hot to the starter was rusted onto the stud on the starter and since I had no idea if the starter was original I replaced it. I can get warranted, so that's the next step.