93 GTP Electrical Headaches

[jkwade]

Hello, first time posting here! I recently joined the W-body community after purchasing a 5-speed 93 Grand Prix GTP. Love the car, very nostalgic, and fun to drive. However, shortly into ownership I found it to have some electrical gremlins which are a bit overwhelming for me to work out (I have experience with cars with OBD2 and cars with a carb and three wires, but this is a new ballgame for me).

 

Basically, the car runs fine most of the time, but sometimes, a relay will randomly start clicking from somewhere under the hood (or maybe in the dash), and when it does, the "Check Engine" light and shift light will alternate lighting up. When this happens, the car starts running much more erratically, with a wandering idle and/or loss of top end. Occasionally during these schizophrenic fits, the engine will still run perfectly fine, but then it will completely die. Last night (for the first time), it dropped idle to about 500, and in order to keep it running, I gave it a little gas. When I did, the revs spiked to 3k (my foot was off the pedal at this point), stayed there, and very slowly dropped by down to idle. This happened a few more times before it cleared up.

 

Is this symptomatic of anything? The battery is supposed to be new, and the terminals look clean. Are there any sensors I should check/clean? Could this be a computer issue? Something else?

 

Sorry if this is the wrong place to post this, or if my question is no good. I can usually figure these things out, but when it comes to electronic issues like this, it helps me to know where to start.

[55trucker]

Do you have access to a scanner?....even a code reader for OBD1?

 

if neither one can get access to any stored codes via a paperclip grounding the test terminal in the ALDL port under the dash panel.

 

The check engine will start flashing, it always flashes a code 12 first,  1 flash...short break..2 flashes. any other stored codes will be flashed afterwards in the same manner, after all have flashed the 12 should flash again to end the cycle. The code range is from code 12 to 66.

 

If the engine idle is off the prescribed by more than 300 rpm for more than 45 secs a code 35 will set (idle speed control circuit).

Run thru this procedure & post back what codes you're seeing.

 

Both the check light & the shift lamp are ECM driven.

 

If you can pinpoint the relay you're hearing that would be beneficial.

 

Do you have any idea as to what the history of the car is?

[Imp558]

If you have a FLASHING "Check Engine" light that's bad news. It should not be driven until it's resolved.

[Addicted To Boost]

Check to make sure your remote positive terminal is tight.  I've had that come loose before and cause all kinds of crazy issues.

[Dark Ride]

Grounds too, have had a loose or corroded ground give me all sorts of weird issues.

[crazyd]

Yeah, it sounds to me like the clicking is a symptom more than the problem.  I think you've got a loose connection somewhere that is causing this.  If your codes come back clean, then as previously mentioned check your battery terminals are tight, the remote positive terminal that is on the right side of the engine bay next to the intake snorkel, the grounds that are on the front of the transaxle bellhousing, and the starter connections.  There's also a gray wire that comes off the remote positive terminal with a ring connector that is of critical importance and will cause this.  If that ring connector's wiring is looking even slightly iffy it should be repaired or replaced.

 

Also be sure to share some pics of the car with the group over in the Member's Rides section.

[Imp558]

The Regal used to buzz on occasion. It was the EVAP solenoid cycling quickly.