replacing the bcm on a 1990 reatta

[Guest daddyrichone]

I am having several issues with my 1990 reatta (a/c will stop working and i have to disconnect the battery for a while and it will reset) and (the car will periodically just not turn over.) i am told my bcm is bad. where is this located and is it easy to replace?  

[Guest daddyrichone]

thanks for your response and as for what the bcm has to do with the motor problems( the bcm controls the security and it periodically tells the car there is a problem and not to start) 

[ChrisWhewell]

I think the bcm on my 90 is freaking out also.   Last week, it was randomly intermittently causing actuation of the trunk latch.  Over the weekend, it quit doing that and has shifted to randomly intermittently actuating the door locks to unlock and re-lock again repeatedly.   Welcome to, the Twilight Zone....

[ChrisWhewell]

"loose and/or corroded"

 

So, are you suggesting that an open circuit causes the door locks to actuate ?

[ChrisWhewell]

Thank you.   I've seen suddenly within about the past week two different symptoms of intermittent actuation, one being the trunk solenoid, the other being the door locks.   If these were both on the same circuit, I might be inclined to believe a single splice fault could be involved.  It seems however since there are different buttons on my key fob for door locks and the trunk solenoid, that these are different circuits.  Thus I contemplate the life of the vehicle being approximately 27 years against the statistical probability that two separate circuits would at approximately the same point in time begin to fail and do weird shttt within a week's time.   While such is certainly within the realm of possibility, I tend to think there is a single common cause for both.  I'm thinking that its the module that receives EM radio signals from the key fob, since both symptoms of trunk solenoid and door locks are features of the key fob.  My thought is that whatever module is responsible for relaying these signals, is just having electronic Alzheimers, or an electromagnetic schizophrenia.   I'm not doubting your stating the known issue of underseat splices having corrosion issues at all.   I'm just looking at where the empirical evidence seems to suggest that there's a common cause of both of these symptoms.  

[ChrisWhewell]

Sure.   but you didn' answer my query above and since you obviously know so much about these cars, let me kindly inquire your reply to this once more

 

"

"loose and/or corroded"

 

So, are you suggesting that an open circuit causes the door locks to actuate ?"

I know a smidgen about electronics and am always wanting to learn more, than, splices are known to cause problems.

If you can't elaborate and have contributed all you can, I'm totally fine with that.   I'd just like to pick your gifted mind a little, about how an open in a circuit could cause two different outcomes, my mind is yearning

 

 

 

 

[Barney Eaton]

One day apart, I received phone call from two different Reatta owners with similar problems.

(1) The first and easiest thing to try......disconnect the battery and put a full charge on it.

(2)  Check ground wires....by the battery, on the bulkhead that supports the radiator, you will find two ground locations, one is a stud the other a screw, they both will have several black wires running to them.....tighten

        near the alternator there is a ground wire...tighten that.........on the fender side of the battery there is an "isolated" ground....tighten that.......at the rear there is a ground for the rear lights, I think it is behind the taillamp assembly.

(3) feel the carpet under the seats......if it is damp, take a day of vacation as you will need it to fix this problem.    Multiple wires run under the carpet on both the drivers and passenger sides.  The more common problem is on the passenger side the cables that run front to back in the Reatta are in a plastic tray, if moisture gets in the tray, it works on cable splices in that bundle of wires.  On the passenger side, there are 5 splices and each has 3 or more wires in the splice.   Ronnie probably has information on his site maybe even a video.........the wires are spliced with a STEEL sleeve which rust over time it it gets wet....the key word here is "time" remember these cars are 25+ years old and if water has leaked into the car over the years, you will have a problem.

If you have a Service Manual,  here are some of the Splices and Grounds  (numbers from 1990 manual)  (G = ground, S = splice)

G100, G102, G103, G200, G300, G400, G410 (there are more grounds but these seem to be associated with the problems stated)

S118, S119, S311, S312, S313, S314,S221, S323, S390, S404, S405, S415

If you tackle the job of repairing the splices,  use a brass or copper sleeve and solder after crimping (belt & suspender approach)

 

[Barney Eaton]

Good pictures......I saved a couple ...they might help someone in the future.