PT Cruiser turbo enters limp mode when hot

[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?

Topic

[hondaguy453]

You mentioned “codes”. Are there more than just the P0882?

[Rahul Jones]

Just check if this link helps: http://www.ptcruiserlinks.com/forum/tech-performance-forum/37700-p0882-low-input-signal.html

[Farrar]

[quote=”hondaguy453″ post=202175]You mentioned “codes”. Are there more than just the P0882?[/quote]

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

[Farrar]

[quote=”rahuljones” post=202201]Just check if this link helps: http://www.ptcruiserlinks.com/forum/tech-performance-forum/37700-p0882-low-input-signal.html%5B/quote%5D

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

[Farrar]

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.

[hondaguy453]

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.

[Farrar]

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.

Attachments:

• 812eeed926521987be36cdf128e29168

[hondaguy453]

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.

[Farrar]

Just thought I’d update this since I seem to have fixed it. (Fingers crossed.)

I bought a relay socket and appropriate color wires and terminals to bypass the relay in the TIPM in favor of an outboard relay. When it came time to trace the wires, it turned out that the colors in the wiring diagram were wrong. So I was forced to use my multimeter to probe the connections at the PCM and TIPM and determine which wires were the correct ones.

I cut the signal and output wires at the TIPM and routed them to my new relay socket, verifying continuity to the TCM connector. Then I made a new, fused connection to battery positive, and a new connection to battery negative, and connected those to the new relay socket. After verifying continuity to those, I put a new relay in my new relay socket, replaced the battery, crossed my fingers, and turned the key. It wouldn’t start until I did a hard reset of the computer, but after that it was fine.

I went on a 30-minute drive to get the engine up to temperature, then shut it off, waited a minute, and turned it back on. The symptoms did not return. The transmission shifts normally and the MIL does not illuminate. I made another test drive, about 20 minutes to refuel and back, and the symptoms have also not returned.

Strangely, my new relay’s Ground wire rings to both Ground and +12 with the key off. This worried me but maybe Chrysler uses some kind of floating ground system.

So it looks like I managed to hack my way out of this problem, at least temporarily. If I want to make it permanent, I’ll have to find somewhere to mount the relay (it’s currently just zip-tied to the body near the PCM) and route the wires (+12 runs between the engine and the air box, Ground runs between the body and the air box). I left plenty of length on the new relay socket wires to mount the new outboard relay wherever I want to; for now the extra lengths are just coiled up, zip-tied together, and sitting on top of the TIPM behind the air box.

Anyway, I hope this information is useful to anyone who has the same problem and is tired of replacing TIPMs. New TIPMs aren’t available anymore, and as my experience has shown remanufactured ones are an expensive roll of the dice.

[Author]

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