ASD Circuit Mystery Issue

[Charlie 99 TJ]

To quickly outline the issue, let me explain how it started. I have a need for a kill switch in my 99 tj due to some mischievous friends. One of my switches interrupts the pcm circuit of the ASD relay. (blue and yellow wire) I did a poor job wiring and one of my soldered connections left me stranded. I was unaware that was the issue so I put a jumper in place of the relay because I figured it had gone bad. Eventually I got the chance to clean up my connection from before and resolder the wires.

Now the issue I'm experiencing is an absolute mystery to me. I think as a result of my jumper, the battery died. That was no problem, and I recharged it and put it back in the jeep. With all connections restored, I tried to start it and it has the same issue as before. Crank but no start. After lots of testing, I eliminated the switch and wired the relay up exactly how it was to begin with, but still no start. Here is a list of everything odd it has done over the period of my testing:
-relay chatter from only asd relay
-mystery continuous beeping with no key and ignition off
-strange battery drainage all the time
-threw the asd circuit code(has since gone away)
-threw p1492 (battery temp code)
Things I have tested:
-the relay works well
- the constant 12v has constant 12v
-the constant ground has ground
-the ignition 12v has 12v when ignition is switched
-the pcm ground has continuity with pin 3 of the pcm
-all fuses are in tact

This lead me to believe it is either the pcm, the data the pcm is receiving, or the ignition. The pcm performed fine until I parked it to repair the connection. The same is true for the distributer pickup(cam position sensor) and the crank position sensor. Regardless, I tried and ultimately failed at receiving conclusive results from testing both these sensors. My doubts are high as to both of them going bad so I chose to call that my own error. That leaves in my mind one final problem. The ignition switch. It has always been a little touch and go but nothing a little key jiggling couldn't fix. I find it hard to believe that this could be the issue either as it had worked for so long. I am lost.

I've been at it for a couple afternoons now and may have missed some part of the story which hopefully isn't crucial but everything listed should be correct. Sorry for the whole book of info, but I am beyond lost.

 

[LONGJP2]

I find it hard to believe that this could be the issue either as it had worked for so long.

What would it take for you to believe it?

 

[Charlie 99 TJ]

What would it take for you to believe it?

Well I reckon I’ll get back with the answer tomorrow. Appreciate it

 

[Leroy Brown]

To quickly outline the issue, let me explain how it started. I have a need for a kill switch in my 99 tj due to some mischievous friends. One of my switches interrupts the pcm circuit of the ASD relay. (blue and yellow wire) I did a poor job wiring and one of my soldered connections left me stranded. I was unaware that was the issue so I put a jumper in place of the relay because I figured it had gone bad. Eventually I got the chance to clean up my connection from before and resolder the wires.

Now the issue I'm experiencing is an absolute mystery to me. I think as a result of my jumper, the battery died. That was no problem, and I recharged it and put it back in the jeep. With all connections restored, I tried to start it and it has the same issue as before. Crank but no start. After lots of testing, I eliminated the switch and wired the relay up exactly how it was to begin with, but still no start. Here is a list of everything odd it has done over the period of my testing:
-relay chatter from only asd relay
-mystery continuous beeping with no key and ignition off
-strange battery drainage all the time
-threw the asd circuit code(has since gone away)
-threw p1492 (battery temp code)
Things I have tested:
-the relay works well
- the constant 12v has constant 12v
-the constant ground has ground
-the ignition 12v has 12v when ignition is switched
-the pcm ground has continuity with pin 3 of the pcm
-all fuses are in tact

This lead me to believe it is either the pcm, the data the pcm is receiving, or the ignition. The pcm performed fine until I parked it to repair the connection. The same is true for the distributer pickup(cam position sensor) and the crank position sensor. Regardless, I tried and ultimately failed at receiving conclusive results from testing both these sensors. My doubts are high as to both of them going bad so I chose to call that my own error. That leaves in my mind one final problem. The ignition switch. It has always been a little touch and go but nothing a little key jiggling couldn't fix. I find it hard to believe that this could be the issue either as it had worked for so long. I am lost.

I've been at it for a couple afternoons now and may have missed some part of the story which hopefully isn't crucial but everything listed should be correct. Sorry for the whole book of info, but I am beyond lost.

 

[Leroy Brown]

Boy knows more words that I do with that long assortment you done made me read. Don’t be scared to take her to the shop now. We all know that you ain’t ever had dirty hands.

 

[GavinWilliams]

To quickly outline the issue, let me explain how it started. I have a need for a kill switch in my 99 tj due to some mischievous friends. One of my switches interrupts the pcm circuit of the ASD relay. (blue and yellow wire) I did a poor job wiring and one of my soldered connections left me stranded. I was unaware that was the issue so I put a jumper in place of the relay because I figured it had gone bad. Eventually I got the chance to clean up my connection from before and resolder the wires.

Now the issue I'm experiencing is an absolute mystery to me. I think as a result of my jumper, the battery died. That was no problem, and I recharged it and put it back in the jeep. With all connections restored, I tried to start it and it has the same issue as before. Crank but no start. After lots of testing, I eliminated the switch and wired the relay up exactly how it was to begin with, but still no start. Here is a list of everything odd it has done over the period of my testing:
-relay chatter from only asd relay
-mystery continuous beeping with no key and ignition off
-strange battery drainage all the time
-threw the asd circuit code(has since gone away)
-threw p1492 (battery temp code)
Things I have tested:
-the relay works well
- the constant 12v has constant 12v
-the constant ground has ground
-the ignition 12v has 12v when ignition is switched
-the pcm ground has continuity with pin 3 of the pcm
-all fuses are in tact

This lead me to believe it is either the pcm, the data the pcm is receiving, or the ignition. The pcm performed fine until I parked it to repair the connection. The same is true for the distributer pickup(cam position sensor) and the crank position sensor. Regardless, I tried and ultimately failed at receiving conclusive results from testing both these sensors. My doubts are high as to both of them going bad so I chose to call that my own error. That leaves in my mind one final problem. The ignition switch. It has always been a little touch and go but nothing a little key jiggling couldn't fix. I find it hard to believe that this could be the issue either as it had worked for so long. I am lost.

I've been at it for a couple afternoons now and may have missed some part of the story which hopefully isn't crucial but everything listed should be correct. Sorry for the whole book of info, but I am beyond lost.

 

[GavinWilliams]

Have you tried putting gas in it?
How about wiper fluid?

 

[Daryl]

Let’s try a simple yet effective method to determine if the problem is fuel or ignition related. Remove the throttle body intake tube. Spray a small amount of starting fluid in the throttle body while a second person cranks the engine over. If it starts, you have a fuel supply issue. If it doesn’t, check for spark.

 

[GavinWilliams]

Let’s try a simple yet effective method to determine if the problem is fuel or ignition related. Remove the throttle body intake tube. Spray a small amount of starting fluid in the throttle body while a second person cranks the engine over. If it starts, you have a fuel supply issue. If it doesn’t, check for spark.

Exactly what I was thinking

 

[Charlie 99 TJ]

What would it take for you to believe it?

No dice. Wasn't in the mood for cleaning contacts etc. so I threw a whole new one in. Same show; crank no start.

 

[Charlie 99 TJ]

Let’s try a simple yet effective method to determine if the problem is fuel or ignition related. Remove the throttle body intake tube. Spray a small amount of starting fluid in the throttle body while a second person cranks the engine over. If it starts, you have a fuel supply issue. If it doesn’t, check for spark.

Good call. Gave it a shot but no luck. It does help to eliminate fuel pump burning out as an issue. It also confirms it is definitely the ASD relay circuit because no fuel and no spark. I'm beginning to worry about it being the PCM. Any good thoughts on how to test?

 

[Daryl]

Good call. Gave it a shot but no luck. It does help to eliminate fuel pump burning out as an issue. It also confirms it is definitely the ASD relay circuit because no fuel and no spark. I'm beginning to worry about it being the PCM. Any good thoughts on how to test?

Good, now you know you have no spark. I would follow the diagnostic flow charts for the codes that are currently present. You’ll find those in the FSM.

 

[B1Toad]

I'm not sure I followed everything but what stood out was relay chatter. When a known good relay chatters it is wired incorrectly. Is it a 5 pin or a 4 pin? If you wired it in such a way that when energized it opens the NC terminal of the relay then quickly closes again due to loss of power it will just do this over and over causing chatter. If the relay chatters, it can't complete either the NC or the NO circuit for more than a split second.
Note: I see you said only the ASD relay chatters, I still think another relay could be the reason, are you sure your kill circuit relay isn't chattering at the same time? (If you used a relay in your kill circuit)
Also note that if the ASD relay is finding a ground thru an un-intentional path like a lamp filament it could chatter as the resistance of the unintended path could be high or even could change with current flow.

 

[Charlie 99 TJ]

Alright, the ASD circuit itself seems to function correctly now. the relay clicks as it should when the ignition is tripped. I also tested the fuel pump by isolating it with a jumper and its all good. With that in mind, I know the fuel pump doesn't run when cranking, the injectors aren't firing, and there's no spark. All that being said I think I have a pcm issue. According to the wiring diagram, the ASD relay circuit sends current back to the pcm where it energizes whatever sets off the fuel pump etc. That leads me to believe Its the pcm. I ran a quick test based on another forums instruction and it looked fine but I know there can be smaller issues without it being all the way fried. Sending it off to get tested is expensive, so before I do so, was curious of any final thoughts.

I am looking into a ship and return service I found on ebay. Is there somewhere else I ought to be looking for a PCM test? Thanks.

 

[OldBuzzard]

@Wranglerfix — best and only PCM service to use.

 

[Charlie 99 TJ]

Wrangler fix got me right. PCM must have been the issue cause it starts and runs now. Hopefully the end of it.

 

[OldBuzzard]

Good to hear.

Is your PCM now color coordinated with your TJ? (usually blue, I think)