22 JLU engineers cannot diagnose

[Firemedic1563]

A month ago my 22 JLU which had not had any issues before 26k suddenly threw a warning at a traffic light that the Start/Stop was malfunctioning and I had to shift from drive to Neutral and back to move. A mile later it had a hard shift and suddenly it seemed like every warning was on and transmission warning came up saying to drive somewhere safe and have serviced immediately. Once in park it shut off but the radio was still on and stuck in “run”. Had it towed after a hassle and got a rental. Dealer diagnosed with help of Jeep engineers as a CANBus issue and it was replaced.
A week later the same exact thing happened. It’s now been at dealer two more weeks and the engineers cannot figure it out. Jeep is now telling me they are starting a buyback process even though I am technically beyond the state lemon law lengths. The service tech said this is not the first time he has seen this. Has anyone had a lasting repair, in case they do not buy it back?

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[richk225]

Consider yourself very lucky!
You actually have a dealer that actually cares about you the owner. Kinda like winning the Lottery

 

[Firemedic1563]

To be clear, the buyback discussion is coming from corporate who I complained to. But my dealer has been great, and explaining to me that the engineers can’t figure it out and even suggested I try to get a buyback

 

[jludave]

in case they do not buy it back?

If it is Jeep/Stellantis offering the buy back, take the offer and run. They will likely proceed with the offer if they cannot diagnose and resolve properly.

 

[Reinen]

It sure sounds like a CANbus issue, but since it was replaced it may be a CANbus issue caused by a faulty wire. In which case it's like finding a needle in a haystack that's hard to take apart.

A buyback is likely your best option. Jump that ship. It will take forever to find the leak.

 

[Firemedic1563]

It sure sounds like a CANbus issue, but since it was replaced it may be a CANbus issue caused by a faulty wire. In which case it's like finding a needle in a haystack that's hard to take apart.

A buyback is likely your best option. Jump that ship. It will take forever to find the leak.

Thank you, that was my thought too. I definitely want out of it at this point before warranty is up

 

[alphawolff]

A month ago my 22 JLU which had not had any issues before 26k suddenly threw a warning at a traffic light that the Start/Stop was malfunctioning and I had to shift from drive to Neutral and back to move. A mile later it had a hard shift and suddenly it seemed like every warning was on and transmission warning came up saying to drive somewhere safe and have serviced immediately. Once in park it shut off but the radio was still on and stuck in “run”. Had it towed after a hassle and got a rental. Dealer diagnosed with help of Jeep engineers as a CANBus issue and it was replaced.
A week later the same exact thing happened. It’s now been at dealer two more weeks and the engineers cannot figure it out. Jeep is now telling me they are starting a buyback process even though I am technically beyond the state lemon law lengths. The service tech said this is not the first time he has seen this. Has anyone had a lasting repair, in case they do not buy it back?

The inline connector behind your right front fender liner has spread/broken terminals/crimps. Instruct your dealer to run overlays around the connector for the TCM CAN +/- circuits, CAN DPT +/- circuits, and TCM power/ground circuits. Usually the power is the culprit, but it could be any of them. Running overlays around this connector is OK as the only time this connector is disconnected for service is when you're taking the body off the frame, and if you're doing that then re-splicing 6 wires is not a big deal.

This is a very common problem and hard to diagnose if you do not know what the issue is, as the pins do not visually look bad/the crimps on the back of the pins aren't able to be inspected. When this issue occurs you can verify the concern by seeing that the TCM is offline on the vehicle network. Usually unplugging and plugging this connector back in will fix the issue momentarily, but it will occur again later. The fact you couldn't turn the vehicle off further indicates this, as a TCM park signal is required before the ignition will allow itself to turn off.

The only way to see it on a meter would be to check the far ends of the circuit, aka checking the resistance of all the above circuits at the TCM itself and the source. Most technicians will test it at the inline connector resulting in the circuits appearing OK, as the issue is on the backside of one/both of the inline connector.

 

[richk225]

The inline connector behind your right front fender liner has spread/broken terminals/crimps. Instruct your dealer to run overlays around the connector for the TCM CAN +/- circuits, CAN DPT +/- circuits, and TCM power/ground circuits. Usually the power is the culprit, but it could be any of them. Running overlays around this connector is OK as the only time this connector is disconnected for service is when you're taking the body off the frame, and if you're doing that then re-splicing 6 wires is not a big deal.

This is a very common problem and hard to diagnose if you do not know what the issue is, as the pins do not visually look bad/the crimps on the back of the pins aren't able to be inspected. When this issue occurs you can verify the concern by seeing that the TCM is offline on the vehicle network. Usually unplugging and plugging this connector back in will fix the issue momentarily, but it will occur again later. The fact you couldn't turn the vehicle off further indicates this, as a TCM park signal is required before the ignition will allow itself to turn off.

The only way to see it on a meter would be to check the far ends of the circuit, aka checking the resistance of all the above circuits at the TCM itself and the source. Most technicians will test it at the inline connector resulting in the circuits appearing OK, as the issue is on the backside of one/both of the inline connector.

I would think that trying to tell the service manager in this case would not be a good idea especially considering the warranty issue. Personally if it was out of warranty and they were not willing to do anything, I would do as you suggested or even go one step further and purchase the wiring harness in question along with the connecters and just bypass the existing one without even removing it just to see if you are moving in the right direction. You have a valid point on the fix, but why should the owner have to come up with a fix? It almost seems like they want to wash their hands of it and move on. From what I was told at the time my Jeep that was bought back could not be resold and I have no clue as to what happened to it. I wish it was like a insurance issue where I would be able to buy it back at a fraction of what it was worth and apply the fix as you suggested.
After having gone through a buyback myself and knowing what the problem was but the dealer refusing to even try the suggested fix it was bittersweet. I had the dreaded wandering issue and the problem was the steering box. I could have gone with a PSC conversion eliminating the electric steering pump and aluminum steering box but I felt that why should I have to spend $3k of my own money to fix the issue. To me it was a matter of principal and also if I did convert to the new steering box and pump if anything happened down the road it would not be covered by warranty. Believe me it was a difficult decision to make, I had lost all faith in Jeep and the way I was treated and the unbelievable amount of lies that were told to me by the service manager and Jeep Cares (which they don`t by the way, at least in my case) I was lucky enough to recoup all of the money spent on the purchase of the Jeep including sales tax, extended warranty etc.

 

[alphawolff]

I would think that trying to tell the service manager in this case would not be a good idea especially considering the warranty issue. Personally if it was out of warranty and they were not willing to do anything, I would do as you suggested or even go one step further and purchase the wiring harness in question along with the connecters and just bypass the existing one without even removing it just to see if you are moving in the right direction. You have a valid point on the fix, but why should the owner have to come up with a fix? It almost seems like they want to wash their hands of it and move on. From what I was told at the time my Jeep that was bought back could not be resold and I have no clue as to what happened to it. I wish it was like a insurance issue where I would be able to buy it back at a fraction of what it was worth and apply the fix as you suggested.
After having gone through a buyback myself and knowing what the problem was but the dealer refusing to even try the suggested fix it was bittersweet. I had the dreaded wandering issue and the problem was the steering box. I could have gone with a PSC conversion eliminating the electric steering pump and aluminum steering box but I felt that why should I have to spend $3k of my own money to fix the issue. To me it was a matter of principal and also if I did convert to the new steering box and pump if anything happened down the road it would not be covered by warranty. Believe me it was a difficult decision to make, I had lost all faith in Jeep and the way I was treated and the unbelievable amount of lies that were told to me by the service manager and Jeep Cares (which they don`t by the way, at least in my case) I was lucky enough to recoup all of the money spent on the purchase of the Jeep including sales tax, extended warranty etc.

I'm a dealer technician and this is the fix I use to repair this concern. Anything more is just overkill. Replacing both those harnesses is an absolutely massive job that I wouldn't wish upon anyone.

You may be able to get just the connector repair kits for both sides (backordered, probably) and just cut/splice the issue wires and re-pin them properly into the connector if you're looking for a totally perfect fix. As this connector is really only disconnected for cab off service it really isn't necessary. I've only seen a wrangler cab removed once in my entire decade of working for Jeep, and it was a frame replacement job for insurance that should've been totaled anyway. If you're going that deep into the repair cutting and re-splicing 6 wires is barely any additional work, ya know? Cosmetically you'll never see the repair, either, as it's behind the fender liner.

Really depends on how much you want the jeep at the end of the day. If you want out, have them buy it back. If you want it fixed just inform them of the likely repair that's needed. The repair takes maybe 20 minutes to perform, and that's including putting the jeep on a lift and removing the wheel/fender liner.

 

[jadmt]

I'm a dealer technician and this is the fix I use to repair this concern. Anything more is just overkill. Replacing both those harnesses is an absolutely massive job that I wouldn't wish upon anyone.

You may be able to get just the connector repair kits for both sides (backordered, probably) and just cut/splice the issue wires and re-pin them properly into the connector if you're looking for a totally perfect fix. As this connector is really only disconnected for cab off service it really isn't necessary. I've only seen a wrangler cab removed once in my entire decade of working for Jeep, and it was a frame replacement job for insurance that should've been totaled anyway. If you're going that deep into the repair cutting and re-splicing 6 wires is barely any additional work, ya know? Cosmetically you'll never see the repair, either, as it's behind the fender liner.

Really depends on how much you want the jeep at the end of the day. If you want out, have them buy it back. If you want it fixed just inform them of the likely repair that's needed. The repair takes maybe 20 minutes to perform, and that's including putting the jeep on a lift and removing the wheel/fender liner.

curious if this is something that can be done as a preventive measure? ie if a person is not having issues but do it to prevent any down the road type thing. can you describe what overlays are in 3rd grader lingo? thanks

 

[mwilk012]

It is very clear from these continuing discussions that nobody understands what the CAN system is at all. It's fine, the techs working on them usually don't either. You're lucky if a shop has 2 or 3 men that can actually make sense of it.

 

[alphawolff]

curious if this is something that can be done as a preventive measure? ie if a person is not having issues but do it to prevent any down the road type thing. can you describe what overlays are in 3rd grader lingo? thanks

Nah, it's not a failure point. I wouldn't touch it unless there's a verifiable issue. It's also one of many possible causes. It's just frequent enough that it should be noted down incase it happens to you.

Overlays = Run a wire around the harness, bypassing it. In this case you bypass the connector itself and make a hard connection between the two harnesses, as the issue is with the pins themselves which mate and make a physical connection inside the connector.

 

[JeepinChamp]

The inline connector behind your right front fender liner has spread/broken terminals/crimps. Instruct your dealer to run overlays around the connector for the TCM CAN +/- circuits, CAN DPT +/- circuits, and TCM power/ground circuits. Usually the power is the culprit, but it could be any of them. Running overlays around this connector is OK as the only time this connector is disconnected for service is when you're taking the body off the frame, and if you're doing that then re-splicing 6 wires is not a big deal.

This is a very common problem and hard to diagnose if you do not know what the issue is, as the pins do not visually look bad/the crimps on the back of the pins aren't able to be inspected. When this issue occurs you can verify the concern by seeing that the TCM is offline on the vehicle network. Usually unplugging and plugging this connector back in will fix the issue momentarily, but it will occur again later. The fact you couldn't turn the vehicle off further indicates this, as a TCM park signal is required before the ignition will allow itself to turn off.

The only way to see it on a meter would be to check the far ends of the circuit, aka checking the resistance of all the above circuits at the TCM itself and the source. Most technicians will test it at the inline connector resulting in the circuits appearing OK, as the issue is on the backside of one/both of the inline connector.

I'm not terribly familiar with vehicle/FCA CAN bus idiosyncrasies, but I have more experience than I would like on off-highway equipment.

Could a verifiable check be a quick load test of those three circuits with a handy taillight bulb (roughly 4ohms) and some jumper leads... plus a Fluke of course? The power and ground circuits at fault should be able to be identified with a volt drop test right?

I concur the overlay fix is a better option than replacing harnesses when the issue can be isolated. I have also replaced plenty of terminals that have spread juuuuuust enough to cause an overloaded bus... boy do threads like these bring back some bad memories on planters .

 

[alphawolff]

I'm not terribly familiar with vehicle/FCA CAN bus idiosyncrasies, but I have more experience than I would like on off-highway equipment.

Could a verifiable check be a quick load test of those three circuits with a handy taillight bulb (roughly 4ohms) and some jumper leads... plus a Fluke of course? The power and ground circuits at fault should be able to be identified with a volt drop test right?

I concur the overlay fix is a better option than replacing harnesses when the issue can be isolated. I have also replaced plenty of terminals that have spread juuuuuust enough to cause an overloaded bus... boy do threads like these bring back some bad memories on planters .

Normally I'd say yes, but the issue is the TCM can work with 300 ohms of resistance on the power supply circuit for awhile before logic locking itself and going offline, giving the illusion that something else is causing the issue. That being said, just performing a resistance check across the connector is enough to find the issue. Wiggle it a bit and you'll see one of the above circuits jumping around. It's just hard to get to the TCM connector to actually do a proper resistance check, as back probing the inline connector won't give accurate results if it's a crimp that's failed.

I believe I've personally always had power or ground circuit causing the issue, as high resistance in a can circuit would cause corrupted bus messaging and take the entire network down, which makes it way harder to diagnose. I just suggest doing them all at once to completely remove this known fault from the equation.

 

[Drsainzvjl]

I'm a dealer technician and this is the fix I use to repair this concern. Anything more is just overkill. Replacing both those harnesses is an absolutely massive job that I wouldn't wish upon anyone.

You may be able to get just the connector repair kits for both sides (backordered, probably) and just cut/splice the issue wires and re-pin them properly into the connector if you're looking for a totally perfect fix. As this connector is really only disconnected for cab off service it really isn't necessary. I've only seen a wrangler cab removed once in my entire decade of working for Jeep, and it was a frame replacement job for insurance that should've been totaled anyway. If you're going that deep into the repair cutting and re-splicing 6 wires is barely any additional work, ya know? Cosmetically you'll never see the repair, either, as it's behind the fender liner.

Really depends on how much you want the jeep at the end of the day. If you want out, have them buy it back. If you want it fixed just inform them of the likely repair that's needed. The repair takes maybe 20 minutes to perform, and that's including putting the jeep on a lift and removing the wheel/fender liner.

Maybe i am asking too much but could you please share us a picture of the Where exactly to cut

i have the same problem and changed the can bus but didnt work

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