battery drain 1988

[Chuck Linzey]

1988 Cad Allante

Having battery drain problem. If I let car set a few days will not start battery dead. Battery checks good. Alternator checks good. Reading about .89 amp draw on battery with everythig turned off. If I remove fuse number 8 drain drops to .12 I think the .12 is normal. Problem fuse #8 is Central Power supply. Need help anyone had this problem? any answer other than remove fuse 8 every night?

[HawkerDR]

I had 2 battery drain problems on my 91 Allante. The first was the rear deck pull down motor was constatly grounded out draining the battery. I replaced and never had a problem until 5 months ago. Then had my power auto window draining in the up position. As long as I left the windows down the battery was fine, but when the windows were up it drained the battery.

[carnut]

The on board diagnostics can perform many switch tests. Door locks, cruise control, headlight switch etc. My point is that you can verify all these switches turn on and off correctly thru the display on the dash. Allantes were prone to door lock switches not fully turning off causing a drain. As you exit the car and hit the power door lock button, in some cases the switch would not fully close. also as you turn the key in the door lock cyl. not turning it fully to the unlock position will cause a drain. This switch test is also availabile thru on board diagnostics. If, in fact, the central power supply is the culprit, then one from a 88 thru 90 I think? Eldo or Seville will interchange. Log onto www.allantesource and read the post on faulty CPS's.

[Allantesource]

The problem sounds like a bad lock cylinder switch that has failed on. This can be verified through the onboard diagnostics by checking the lock cylinder switches at BCM Input Parameter BI61. What's probably happening is that the switch has failed on so it is continually sending wakeup voltage to the BCM as if you had a key turned in the outside lock cylinder and were opening the door. It's not the CPS causing the problem. There would otherwise be no draw if the switch were not turned on.

[Chuck Linzey]

I have never locked car the top is down from the time I remove top in spring. Cover at night with cover only. No message except battery dead. I have added switch to fuse 8. I turn it off if the car is going to sit for a few days.

[Allantesource]

Locking the car has nothing to do with this problem. The switch on the back of the lock cylinder has probably failed on, sending a constant wakeup voltage signal to the BCM. By pulling or shutting off the power at Fuse 8, you will stop that drain. Correcting the problem would require either disconnecting or replacing the lock cylinder switch.

[Chuck Linzey]

when I return home I will disconnet for a few days and see what hapens, thanks for the help.