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Another plea for electrical advice ... arrgggh!


Guest Geoff Meador

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Guest Geoff Meador

The problem is different than I described it last time, which was based on my wife's second-hand description of the problem. I drove it myself and here is the problem:

While driving, the electrical system will (at random) act as though I've turned the key off. The IPC goes dead and the CRT defaults to the Radio screen just like it does when you kill the car. The radio continues to play and the CRT blacks out after a minute or so.

Meanwhile, the car is continuing to run as normal the entire time.

After a random amount of time, the car will "start up" again. The IPC and the CRT go through their startup sequences and everything returns to normal. There are no error codes generated.

One time I did get a VERY brief (less than 1 second) error message that I think said "Engine Computer Error" or something to that effect. When the system restarted, it was gone. Not even in the history codes.

Anyway, my wife is the daily driver of the car and she hates it right now. If I can't get this fixed, we probably won't HAVE a Reatta by the time next year rolls around.

Maybe someone can help. I'd appreciate it.

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Guest Greg Ross

May have to wait for one of the Wizards to come in with The Answer but sounds to me like BCM. If the Central Power Supply was cutting out ECM would go down too I'd think. All of what you mention are outputs from the Body Control Module, Id say right off the top check grounds first and if that doesn't correct it the next step is to disconnect and reconnect the harness plugs on the BCM it'self......

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Greg has it right. Do you get the "system checks" display when it comes back ? If so would say the BCM is losing its switched power. It has a component of "number of starts" (BD98) -is this value "1" or "0" after a reset ? If dropping to zero after each blackout would look to the battery (mainainance) power line.

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Guest Geoff Meador

If you're referring to the CRT's system check startup procedure, then yes. It's like I just started the vehicle again.

I'll check the number of starts reading tonight. Thanks.

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Guest Geoff Meador

OK, worked on it this evening and have more details to report:

BCM emits an audible hum during the failure.

BCM reports number of starts as "0" even BEFORE the failure.

Only current error code is E047, which is ECM-BCM DATA.

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That sounds like a total power loss, not just CPS. My next step would be to swap the BCM since I have a spare.

Of course since cars I like tend to be kept for 20 years or so, am in the process of laying in a full set of spares & am getting close.

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Guest Geoff Meador

Thanks padgett. On swapping the BCM: aren't VIN and odometer information stored in the BCM? I don't mind swapping the part, but I fear I will regret losing that original info.

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The odo and VIN are in the smaller of the two PROMs under the square cover on the BCM. Just swap it also. Would try out the replacement first with what comes in it, make certain that works, then swap the PROM (unless it comes with no PROMs in which case you need to use both of the originals).

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Guest Geoff Meador

Well, so it continues:

I swapped the BCM today with a genuine Jim Finn® replacement part. Same problem occured immediately.

So it isn't the BCM. Failure occurred, remedied itself, and occurred again while sitting motionless in the driveway so I know it isn't a loose wire getting jostled on the road.

Any further suggestions? My ears are wide open.

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Guest Geoff Meador

Unbelievable! My father-in-law drove the car today for three hours and it performed perfectly.

The difference? He has a like-new, freshly ground ignition key with no other keys on the ring.

My guess is that we have a short in the ignition that is aggravated by either our worn original keys or the other keys adding weight to our keyring.

The car continues to run but the BCM doesn't know what position the ignition is in, maybe? That would explain the "number of starts" staying at zero most of the time. Maybe? <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" />

Has this been documented before?

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Since the actual switch is two feet from the key the only electrical difference the key would make would be if the resistor (you do have a "pass-key" ?) had either changed value or the contacts were getting worn.

Does indicate the next thing to try is a new key. If not you might try juggling the ign switch rod with it running, could be a failing contact on the switch itself.

Looking at the manual I would try to put a test light on 3 amp accy/BCM fuse #15. Is possible that pulling/replacing this fuse with the ignition ON would duplicate what you are seeing.

Just thoughts.

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Guest Brolliar

Geoff, it will be nice if the key, keyring weight or ignition switch is actually the problem. I think your Reatta is a 1988, right? Please let us know if this is still the solution a month from now.

Good Luck.

Dick

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Sorry Geoff, I missed the "'88" at the bottom (brane-fade). That means you do not have a pass-key which from my parts book was not used until 1990.

My "gut" feeling is a worn ignition switch or a misadjusted switch rod - see the end of section 3B4 in the service manual.

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