PT Cruiser turbo enters limp mode when hot

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2 weeks 3 days ago #202137 by Farrar
Vehicle:
2006 PT Cruiser turbo (8-series VIN)
TIPM replaced in 2016
PCM replaced in 2018
Reman trans (A604/41TE - 4 spd auto) installed 2017, all new sensors & solenoid pack
Battery less than 3 years old, has been tested last week and is good
Brand new ground straps installed last week, engine to transmission and transmission to battery negative

Situation:
No problems when started cold. When hot, will not start on first turn of key, have to try a few more times, "check engine" turns on, vehicle starts and I am in "limp mode" until the engine sits for at least five hours to get fully cold *AND* I clear the codes.

P0882 would seem to indicate low input voltage to TCM, but TCM is integrated in PCM and TCM relay is integrated into TIPM. How do I troubleshoot this?

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1 week 6 days ago #202175 by hondaguy453
Replied by hondaguy453 on topic PT Cruiser turbo enters limp mode when hot
You mentioned "codes". Are there more than just the P0882?

If it ain't broke, don't fix it
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1 week 4 days ago #202201 by rahuljones

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1 week 3 days ago #202228 by Farrar
Replied by Farrar on topic PT Cruiser turbo enters limp mode when hot

hondaguy453 wrote: You mentioned "codes". Are there more than just the P0882?


Just P0700, which is the MIL light turn-on request.

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1 week 3 days ago #202229 by Farrar
Replied by Farrar on topic PT Cruiser turbo enters limp mode when hot

rahuljones wrote: Just check if this link helps: www.ptcruiserlinks.com/forum/tech-perfor...ow-input-signal.html


Thanks, I will check that harness by the battery tray and see what I can find.

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1 week 3 days ago #202230 by Farrar
Replied by Farrar on topic PT Cruiser turbo enters limp mode when hot
I'd like to check the relay, but it's inside the TIPM and I don't know how to access it. Once I remove the cover of the TIPM, I can see the fuse tray, which is held on with a few Torx screws. I can remove the screws, but the tray doesn't move. It is also not accessible from underneath.

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5 days 2 hours ago #202258 by hondaguy453
Replied by hondaguy453 on topic PT Cruiser turbo enters limp mode when hot
I would start checking power and ground coming from the relay going to the PCM. You'll probably have to make the system fault before doing so, but I'd check it while the vehicle is operating normally to get some numbers to compare to. You'll need a wiring diagram of course, or you can look at some vid's on youtube about this specific problem. I found one and it's what I'm using right now to give you suggestions.

If it ain't broke, don't fix it
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The following user(s) said Thank You: Farrar

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2 days 13 hours ago - 2 days 13 hours ago #202299 by Farrar
Replied by Farrar on topic PT Cruiser turbo enters limp mode when hot
I got hold of a wiring diagram.

The relay receives +12V through Fuse #15. (red/white wire)
The trigger is from the PCM Connector 4, pin 18. (light green wire)
The output is to the PCM Connector 4, pins 19 and 28 (red wire, spliced to split the output).

The ground goes to a splice, but I can't physically follow the ground wire because it's all wrapped up in a harness that disappears to where I can't get to it. Knowing that old cars almost always have grounding problems, I'm tempted to just see if re-routing that ground connection directly to a known good ground might solve the issue, but I also know that Chrysler TIPMs are notoriously bad, so it's probably not just a bad ground.

It looks like I can troubleshoot this situation by temporarily bypassing the relay on the TIPM with a standard 12V relay. I have a couple of spare Bosch-type relays from another project. I'm going to order the appropriate wire (color and gauge), then try the bypass. If the problem goes away, then I can think about replacing the TIPM, or maybe just mount the new relay somewhere appropriate and call the job done.

EDIT: Wiring diagram attached.
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Last edit: 2 days 13 hours ago by Farrar. Reason: clarification, added pdf

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24 minutes ago #202327 by hondaguy453
Replied by hondaguy453 on topic PT Cruiser turbo enters limp mode when hot
You can try wiggle testing the harness to see if you can make the vehicle fault before it gets up to operating temp. Since the fault only occurs once the vehicle is warm, it sounds more like a module problem, though I could definitely be wrong. You can try checking voltage while the engine is cold and hot to see if anything drops off, but depending on how fast it switches, a regular dmm might not catch it. Try tapping on the TIPM too before the engine gets hot. Maybe you can make it fault that way.

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