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Diagnose Cruise control '96 Regal


Chip

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I have a 1996 Regal Custom 3.1

 

The cruise stopped working some time back. Where to start with diagnosing. The switch on the turn signal stalk does not "feel" any different. I had the steering column apart to replace the turn signal switch and the wiring appears intact. I know that light guage stuff has a tendacy to crack and break like on the VATS system.

 

I would like to rule out some of the obvious (not to me apparently) things that some of you may be able to suggest.

 

Thanks in advance for any help.

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I have a 1996 Regal Custom 3.1

 

The cruise stopped working some time back. Where to start with diagnosing. The switch on the turn signal stalk does not "feel" any different. I had the steering column apart to replace the turn signal switch and the wiring appears intact. I know that light guage stuff has a tendacy to crack and break like on the VATS system.

 

I would like to rule out some of the obvious (not to me apparently) things that some of you may be able to suggest.

 

Thanks in advance for any help.

 

when you took the steering column apart to replace the turn signal switch, did you actually replace the turn signal switch? Or just look at it and figure that the wiring looks fine so it must not be the switch.

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Actually, here's what happened. I was going to change out the entire TS switch, but when I found that the two self cancelling springs were broke and more easily replacable that taking the entire switch out, I just installed new springs. The switch itself was never really changed. The kicker is that although the turn signal stalk will now stay in place and self-cancel, the turn signal does not work unless you partially depress or raise the stalk. Could the TS switch play a role in this?

 

Thanks for the quick response.

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If the cruise control is getting a signal that the brake lights are on maybe the TSS is backfeeding the brake light circuit and kicking the cruise out?

 

Do your brake lights work normally?

 

I don't know if 96 cruise is vacuum accuated or not but make sure all the lines are hooked up and the vacuum ball in the LF fender is intact.

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Start by checking your cruise control switches. Use the multimeter and check for continuity of this circuit (please see the attached diagram). There are 4 colored wires that going from the lever to the socket on the steering wheel column. On my 95 GP, the Set/Coast button was constantly on, canceling the cruise operation. I ended by cutting the wires (1 and 2 on my diagram; I don't remember the color of the wires) and soldering them to the microswitch which I glued to the end of the lever. Actually, the microswitch replaced the defective button.

If the switch is OK, find the diagram for your vehicle and check the wiring harness of the cruise module (+12V, ACC). The module also receives the signals from the PCM and speed sensor, but it could be more difficult to check these signals.

 

Anton.

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If the cruise control is getting a signal that the brake lights are on maybe the TSS is backfeeding the brake light circuit and kicking the cruise out?

 

BINGO. you must rebuild or replace the TSS. If you take it apart and the contacts are not worn, you can clean them bend them to increase tension, and then you must lubricate them to prevent further corrosion and wear. Dielectic(silcone) grease would be best.

 

On my cars I have added LED indicators to tell me what the lights on the rear of the car are doing. but I digress, like normal... :lol:

 

 

 

You MUST to the following to see what does not work, it requires a nice mirror or window reflection or a second person, and each step requires a bulb check, and note when a bulb should be on but isn't.

*key in run, engine does not need to be on, but it can be*

apply brakes.

apply left turn signal

apply right turn signal

apply brakes and left turn signal

apply brakes and right turn signal

apply hazards

apply hazards and brakes.

apply hazards and left turn signal

apply hazards and right turn signal

apply hazards and brakes and left turn signal

apply hazards and brakes and right turn signal

 

The crux that many people do not understand is that sometimes the brakes lights do not work under any one of the preceeding circumstances, but they work the rest of the time.

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Also, keep in mind that the brake light switch under the dash is actually TWO switches, so it is possible that the brake lights operate normally, but the second switch, which disengages cruise may not.

 

A scantool could tell you very quickly if the switch is operating properly.

 

 

If the cruise control is getting a signal that the brake lights are on maybe the TSS is backfeeding the brake light circuit and kicking the cruise out?

 

BINGO. you must rebuild or replace the TSS. If you take it apart and the contacts are not worn, you can clean them bend them to increase tension, and then you must lubricate them to prevent further corrosion and wear. Dielectic(silcone) grease would be best.

 

On my cars I have added LED indicators to tell me what the lights on the rear of the car are doing. but I digress, like normal... :lol:

 

 

 

You MUST to the following to see what does not work, it requires a nice mirror or window reflection or a second person, and each step requires a bulb check, and note when a bulb should be on but isn't.

*key in run, engine does not need to be on, but it can be*

apply brakes.

apply left turn signal

apply right turn signal

apply brakes and left turn signal

apply brakes and right turn signal

apply hazards

apply hazards and brakes.

apply hazards and left turn signal

apply hazards and right turn signal

apply hazards and brakes and left turn signal

apply hazards and brakes and right turn signal

 

The crux that many people do not understand is that sometimes the brakes lights do not work under any one of the preceeding circumstances, but they work the rest of the time.

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Also, keep in mind that the brake light switch under the dash is actually TWO switches, so it is possible that the brake lights operate normally, but the second switch, which disengages cruise may not.

 

A scantool could tell you very quickly if the switch is operating properly.

Incorrect. The brakelight switch is wired to the cruise control. a backfeed of power from the tss is the culprit in tripping the cruise control to disengage.

 

 

 

ADDED FOR CLARITY:

 

There can be more than one switch down there. BUT only one of the switches or contacts within the mutlipart/multiswitched brake switch is dedicated to the TSS and brakelights. the other portions have the deal with the TCC release. 92ish+ cars use a simple block switch with actuated by a plunger, and 92ish- cars have a multiform levered switch. that is more complex and less reliable.

 

It is unlikely a first gen GP will have issues with the TSS. The rear brakelights and turnsignals in that model are on separate circuits therefore use separate bulbs, so brakelight power is not shunted through the TSS.

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