Electrical starting system shutdown-could be nuclear meltdown

[Dave2]

I'm in the process of diagnosing what initially appeared to be a dead cell in a battery on my 1992. The car battery was on a battery maintainer (green condition light on). I had plans to start the engine and service the vehicle for spring. When I got in the car, I had no interior lights, and a strange clicking from the PS dash. Pulling the LCD fuse would stop it. Replacing the fuse, I attempted to start the car and that was the point the dead cell in the battery was discovered (10v). So much for the green light on the maintainer. I replaced the battery. I reattempted starting the car and discovered: no starter engagement, still had no interior lights, dash LED, no security indicator, or door chime. Headlight are nice and bright. I re-tried starting the engine 24 hrs later (assuming there was a timer) with the same results. I'm not sure what components could have been damaged in a prolonged low voltage situation. I have had suggestions this may be VATS related. Where should I start on diagnosing this?

[tpr60]

If you have a spare ign. key try that first. Some times the resister inbeded in the key goes bad, or the lock cylinder can't read the chip.

[Schrade]

Welcome onto the boards here...

Pocket lint (and other gummynastyjam) on the key pellet can interfere with key reading properly in the ignition.

The clicking, I believe, is the Delayed Accessory Bus. Whether or not DAB is on the LCD circuit, as you pulled the fuse, I'm not certain.

You'll get proper diags from some of the gurus on the boards here yUp......

[scottfab]

Great write-up and isolation points you've offered up.
Headlights bright and no interior lights are great to know.
Not very likely the key pellet or key at all.

OK sure sounds like corrosion on the main acc bus post
but could also be corrosion at the battery ground.
The acc bus post is located just next to the battery. It's just
to the right of the battery (toward the firewall).
Here is a pic of the area (battery and battery base removed) but the post is just off screen to the right.


You may need to remove all the lugs off the acc bus post, clean each then re-attach all lugs applying dielectric grease to all.
First, do measure the new battery voltage right at the posts as someone turns the key. If it drops below 11V your new battery ain't worth squat.

[Schrade]

Is this the same as the DAB? With the integrated timer ? Or is that a different gizmo?

Originally Posted by scottfab

[scottfab]

That is the INFL REST sensor on the drivers side.

[Dave2]

I'll check for corrosion at the main acc bus- but whole area was very clean when I swapped the battery- 30k miles on car serial#0202. When I turn the ign. key there is no sound (click)of any power reaching the starter solenoid- although I may hear the fuel pump cycle in the rear...? The vacuum pump (I believe PS front engine compartment will cycle for a few seconds when the key is turned on, and then stop. I'll also try the spare key. I did find a link for locksmiths related to VATS keys making and problem diagnosis that indicated that no security light flashing on the dash required a VATS repair b/4 a new key could be checked- https://www.lockmasters.com/ecommerc...%20Article.pdf Not sure how credibile the article is though?

[scottfab]

Originally Posted by Dave2

I'll check for corrosion at the main acc bus- but whole area was very clean when I swapped the battery- 30k miles on car serial#0202. When I turn the ign. key there is no sound (click)of any power reaching the starter solenoid- although I may hear the fuel pump cycle in the rear...? The vacuum pump (I believe PS front engine compartment will cycle for a few seconds when the key is turned on, and then stop. I'll also try the spare key. I did find a link for locksmiths related to VATS keys making and problem diagnosis that indicated that no security light flashing on the dash required a VATS repair b/4 a new key could be checked- https://www.lockmasters.com/ecommerc...%20Article.pdf Not sure how credibile the article is though?

Since you previously posted there was no security light (flashing or other wise) I'd say it's not the key. Focus first on the "new" battery. See what it does when turning the key. It should not sag too much. Take each terminal off and inspect for anything in the way. then start looking down stream from there. (acc post)

[Dave2]

I got a Chevrolet service manual and the diagnosis is pointing to physically checking the CCM. How hard is it to get to the CCM, and is this unit replacable or rebuildable?

[tomtom72]

The CCM is buried behind the bezel that frames the DIC/A-C & radio. If I remember right the stack of stuff has to come out, and then the DREM comes out ( discon battery & wait 15 mins for SIR system to loose stored voltage ) and then it's under the DREM....I think? Or behind more to the firewall? Sorry, senility stinks!

Console has to come out. Remove the shift knob & rev lock out ring by prying up pattern plate & pull out the "T" wedge & unscrew knob. Locate all the 10 mm small bolts for console under lid & ashtray. Then remove the A/C register above DIC. You'll see the screws holding the bezel in place, BUT be aware of the two spring clips about the mid point of bezel. I snaked my fingers to both sides of each clip and pulled evenly on the left & right sides of the bezel to get them out. Careful or the bezel could break. Then discon the power key harness & then the DIC & A/C & Radio can be removed. That's the short version of the procedure.

There is one other possibility that is just as distasteful : the ignition key cylinder has a wire that is prone to breaking off the cylinder. Somehow I'm not sure this is a worthwhile suggestion to run down until you exhaust all the other possible causes for no start.

You are absolutely sure that all the battery connections & grounds are 100%? I'm not trying to be a wise guy. The battery was charged & load tested? Hydrometer tested? & Last a volt reading? The CCM maybe NLA from GM. A new one needs to be reprogrammed or loaded with your CCM's info or the car is dead. I think if you call Gordon Kilbrew or Marc Haibeck they can suggest where to get your CCM rebuilt....I think?


Tom