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1998 Grand Caravan OBD-II code P1698

My service engine soon light came on and the guy at O'reilly's put the OBD-II on it and P1698 came up. This has something to do with the TCM not communicating with the BCM or some such thing. I have been searching all over the web for P1698 and it seems to be usually associated with dash lights and gages being intermittent. Our gages are intermittent but right now are working fine. They say they fix is to take the instrument cluster out and resolder the grounds to the main connector. That seems to get rid of the light and the P1698 code.

But if P1698 is that the TCM does not talk to the BCM, how does the cluster get into this?

I guess my real question is what do I do to get the light to go out and the code to go away? Resoldering the cluster just doesn't ring true with this code description, but on the other hand, the description is not much of a help either.

Any assistance would be greatly appreciated.

mspart

Comments

  • I know the instrument cluster needing resoldering is a common problem. Seems like you are on the right track. I assume if the connection between the BCM and TCM is interrupted then you get a code. You already have the intermittent cluster issue. The best place to start would be the soldering, then if that doesn't fix it have to get a second opinion.
  • Thank you galant,

    I think I will try to clear the message first with a borrowed OBD-II tool. If that does not work, I will see about the solder job. I'll let you know what I find.

    If anyone else has any info about this, I would very much appreciate any direction that can be given.

    mspart
  • The message cleared with the OBD-II tool. I suppose if it comes back it is to the instrument cluster I go.

    Thanks for the help.

    mspart
  • Fault P1698 is for a loss of communication between the PCM and the TCM. There are about a half dozen computers on the CCD bus (network). When the communication on the CCD bus stops or is interrupted faults may be stored in a number of computers. The computer you are accessing for fault codes is the PCM, which has turned on the MIL but this won't tell you where the problem is.

    The problem may be the BCM or instrument cluster. The problem could be anywhere on the Bus circuit, I have found radios that shorted the Bus circuit.

    Give the instrument cluster repair a try, if that doesn't repair it diagnosing this will be difficult for the do-it-yourselfer.
  • It would be interesting to know if the gauge trouble happens at the same time the code appears. My first suspect for the cause of the code trouble would be intermittent power to the TCM. I would check to see if the TCM is on the power circuit as the gauges are. If so, that would make even a better case to look at a power connection problem as the culprit for these troubles.
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