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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.
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.
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.
[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.
[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.
Thanks.
Battery shows 12.6 Volts at rest. While running, system voltage is 13.8 Volts. I think that both of those numbers are within spec, but I can clear the codes and start the engine with a booster battery connected to see if the codes show up again.
According to the service manual, the Transmission Fluid Temperature Sensor is part of the Transmission Range Sensor. I’m not sure how to test that for voltage, since accessing it involves removing the battery and battery tray. The transmission allegedly came with all new sensors. I wouldn’t expect one to fail so soon, but I suppose anything’s possible. I can at least inspect the connector for corrosion or damage.
I appreciate your suggestions! You’ve given me something else to look for.
[quote=”nightflyr” post=196267]My first thought would be to correct the – P1603: PCM Internal Dual-Port Communication Failure.[/quote]
And how would you do that?
Shot in the dark – but maybe something is sticking in the throttle body? If you have a mass air flow sensor, maybe make check to see it is also clean and has a good electrical connection.