96 Buick Regal intermittent starting problem - SOLVED!

A friend just bought a 96 Buick Regal. Afterward he drove it to my place from the DMV to show me. Then it wouldn’t start when he left for home. Turn the key to Start, and nothing, no clicks, nada. Then after a few more tries it started right up, no problem. This behavior continued the next day, which is today. I went to his place and putzed around to get familiar. I ended up applying 12 volts to the solenoid wire at the starter with the key in the Run position. Engine cranked, started and died, a few times. OK, so the starter is good, the battery is good. I tried starting in neutral instead of park. No difference. I had my friend do the actual starting with the key. Then I tried starting the engine with the key. I found that when I jiggled the key in various ways, the engine started damn near consistently after about 7 or 8 tries… until it didn’t. The usual jiggle didn’t work… until it did again. At this point, the ignition switch seems like a likely suspect. But the fault might be in what is called the “theft deterrent relay” and the “theft deterent module” both of which can be seen in the diagram linked below, and I might be imagining that the jiggling completes the critical circuits to start the engine. Try as a might, I could not find these two components on short notice, using the internet and my own experience, limited as it is. Any thoughts, suggestions?

PS - My 87 Dakota auto transmission is running fine.

1996 Lumina starting circuit, similar, if not identical, to 96 Regal

I’m going with the ignition switch failure. If it was the antitheft it couldn’t have been driven home. When jiggling the keys changes behavior points to ignition switch.

I will throw out that the ground strap for the heck of it. Can’t remember if they still used those that late into the mid 90’s. But worth a check.

Before doing anything, check the positive battery terminal for corrosion.

GM vehicles of this vintage were notorious for this problem.


Those are all good suspects. The transaxle range switch is possible too for a no-crank. Jump starting could confuse the computer, it might expect a “start” signal appear as an input before it will allow the engine to run. A possible explanation for why you can jump start , starts, but doesn’t stay running.

The anti-theft relay from what I can see is located above the glove compartment, behind the instrument panel. The relay and module are side by side. If you measure +12 on pin A2 of the relay (yellow wire), but not on C1 (purple wire), that means the relay is off (open circuit).

If I had this problem I’d first check the voltages directly at the starter motor. The big wire terminal and the little wire terminal should both measure 10.5 volts or more when the key is in “start”. Do they?

Turns out the problem was the two small white wires going up the steering column to read the resistance on the chip on the key blade. The wires get frayed after repeated turning of the ignition switch. I measured the resistance on the key and put together two resistors to equal the value expected by the Vehicle Anti-Theft Systen (VATS). I unplugged the two wires from the connector and replaced them with the resistors so that the VATS is always reading the correct resistance. Engine fired right up everytime after doing this. Here are the links that helped:

The two little white wires
How to Find KEY resistance in GM PASSKEY Chip
Eliminated the key resistance read