Alright, more electrical gremlins on my '94, LT1, Auto.
It has sat for a few years under a cocoon in my driveway. I start it about every 3 months, maintain the battery, etc. It has 80,000 miles.
I'm getting the weatherstripping replaced, new windshield, new hood paint etc, to prep for selling it in the spring.
I went to start it a few days ago and the battery was dead.
I removed the battery, charged the battery, 10 amp for 10 hours, it tests good (14 volts). When I reconnected the battery I could hear the EGR purge valves clicking up front, and the horn click from the security system.
I now have power to the following: ALL dash gauges, except the digital readout for speedo, fuel etc.
Radio works, headlights, courtesy lights, windows, locks, heater fans etc.
When I turn the key I can hear the fuel pump charge the line.
I checked all fuses, mini, and maxi, including ohming the fuse blocks, all good.
The Chilton is junk for higher level troubleshooting, especially electrical.
Can anyone offer advice on a common ground for the ignition and digital readout? I know grounding was a problem with the C4's since there really is NO real metal body.
I am currently checking all of the ground strap location I can find, jacking it up to check the starter solenoid. Unless there is multiple problems, I don't see how the starter solenoid could affect the digital display not working.
I have also tried starting the car in Neutral, rocking it back and forth in case the tranny switch is stuck, gear selector works with the foot on the brake.
If I remember correctly the digital display came on before the START position and worked without the the engine running?
I drive an '02 and have forgotten a lot about what I should be seeing in the '94.
Help?
UPDATED: I jumped the starter solenoid with the hot cable going to the starter and the engine started. It would only run for about 5 seconds then die. So I know the starter solenoid works, and I am getting power to the starter, and it is grounded. So is there a relay outside of the ignition switch between the fuse block and starter?
I am starting to suspect the ignition itself.
I tried all three of my key sets in case the ohm resistance chip could have been damaged in one. All three act the same, and chips ohm the same.
Am I missing some kind of security feature that disables the ignition if the ignition is attempted to bypass, (removal of the battery)???
Any help would be appreciated.

RACER X

 

There is a power stud behind the battery, down near the tray, that has multiple red wires on it, that feed several circuits. You could check there for looseness and/or corrosion.

 

Thanks Sailor, I checked that. It feeds a block of maxi fuses, which includes the two 60 amp ignition fuses. It was a little crusty. I removed the fuse block, cleaned all contacts and wire ends. I also tested the two fusible links at that location, which although they look like they got hot at one time, ohm out and allow 14 volts through.

I see in the electrical schematic a "Theft deterrent Module" that gets juice from the ignition switch and allows power to the tranny switch. I cannot find it I would like to try and bypass it.
The Tranny and brake system switches seem to be working, whereas I must step on the brake to change gears. and the igintion will not let me turn it to "OFF" if the tranny is in "NEUTRAL".
There is NO 12 volt power to the starter solenoid with the key in the START position. Although I can get the car started by jumping power to the starter solenoid, the digital display never comes on, and the engine wqill not run longer than 10 seconds. ALL fuses that I can locate are good.
Anyone taken their igntiion switch out before? It looks like a LOT of work but I am suspecting the switch itself more and more, even though it has never acted up before. WTF?

Anyone?.....Anyone?.... Buhler?

 

OK...Still going unless someone wants to chime in.
TODAY: I purchased an on-line manual for the '94 through all data diy.com. I located the Starter Enable Relay lickity split thanks to a clear, concise electrical diagram. (NICE website by the way.)
I hunted down and replaced the "Starter Enable Relay" tucked away under the dash like Jimmy Hoffa's corpse. I think the electrical engineer should have his head examined.
NO change.
I tracked down all of the exterior grounding locations, cleaned, then reattached ground straps.
NO change.
I found the two thin white wires from the VATS reader in the ignition down the column. They are not broken. I will research here tonight on how to bypass / disable the VATS system just to see if that is the problem.
I am also going to try and find the ground from the digital display and ohm it to a good ground to see if there is continuity.
Still NO LED display, which is worrisome since they are $350 to rebuild.
I NEED AN EXPERIMENT DONE FOR THOSE THAT OWN A '94 COUPE:
Can you tape over the resistor on your key, insert it and see if the digital display lights up? That could be a BIG help.
I live in the mountains where all of our authorized GM dealers / GM dealerships went belly-up a few years ago. My closest GM repair is now about an hour away.
Thanks for looking.

 

Been cruising my '92 FSM. Don't know how different the two systems are, but they use the same style dash. As you guessed originally, the dash display should turn on with the key in the "run" position.

In the '92, the LCD display ground is the one in the driver's footwell. If yours is the same, the ground must be good, because other circuits that use this ground work, and it is unlikely that the ground path from the display to this stud has been disrupted, especially since you have other issues at the same time.

I think both years have a similar anti-theft system, they called it PASSkey, with the same type of chip in the key. I think you may be right to suspect this system, as it disables cranking and fuel delivery when activated. When you jumped the solenoid, the car started and ran using the built-up pressure in the rail, then stalled. If you can lay hands on a GM TechI or TechII you can pull codes from the ECM and the CCM that would point you in some direction. There may well be a problem with the ignition switch not correctly reading the pellet resistance in the key. The '92 will self-read these codes, don't know about the '94, but in any case, The CCM codes would be displayed on the LCD display (which doesn't work) and the ECM codes need the key to be on.

 

There is a bunch of information on VATS here:

http://www.vatssucks.com/

He only goes up to 1993, but the system probably didn't change for 1994.