Bad brake switch under dash

GNRick

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The brake switch wasn't sending the signal down to the torque converter. So I tried two new switches. First one from Oreilly's (BWD) for $13. I played with the plunger about 10 times, worked fine, then it quit sending the signal. Couldn't hear the TCC solenoid and checked for 12 volts. Nada. So then I went to Advance and bought the cheaper one for $7.99. Pressed the plunger in, worked fine for 3 plunges, then nada. I checked for 12 volts right on the switch. Nothing. Brake lights continue to work so I know the switch is getting power. Anybody else have this issue? Just ordered two GM switches from Rock Auto for $14 each. I hope I have better luck.
 

earlbrown

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Brake lights continue to work so I know the switch is getting power. .
That's not accurate. Just because the brake lights are getting power doesn't mean the hot side of that switch is getting power.

The only way to know for sure is to put a meter on it.
 

GNRick

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The switch has two hot sides. One side has three wires that activate the brake lights. So one of the wires is hot coming into the swich. The other side has two output wires....a purple and a grey. The purple goes to the transmission for TCC lock up. I believe the grey must be for the cruise control. I put a meter on the connector for the purple wire and there was no voltage showing. Same for the grey wire.
 

v6turbo87

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There is a separate switch for the TCC 12 volt signal. It does not come fron the brake light switch.

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v6turbo87

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Sorry my mistake there is a separate switch for the cruise control. There at two connectors in the brake switch. When you step on the brake it opens the 12 volts to the TCC solenoid. There should be normally 12 volts to the TCC solenoid all the time assuming you don't have your foot on the brake. The ECM grounds the other side of the TCC solenoid for lock up. Check the connector down at the transmission with a voltmeter. I don't know the pinout but one of the leads should have 12 volts key on engine off.

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GNRick

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Sorry my mistake there is a separate switch for the cruise control. There at two connectors in the brake switch. When you step on the brake it opens the 12 volts to the TCC solenoid. There should be normally 12 volts to the TCC solenoid all the time assuming you don't have your foot on the brake. The ECM grounds the other side of the TCC solenoid for lock up. Check the connector down at the transmission with a voltmeter. I don't know the pinout but one of the leads should have 12 volts key on engine off.

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I checked the purple wire (top left when the plug is connected to the transmission) down at the transmission and there was no signal when the brake switch was actually working. So I spliced in a new wire and that fixed that problem. Then the brake switch decided it had enough and quit working.
 

GNRick

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Ok maybe this will shed some light on the subject. And maybe John Spina will chime in, as he gave me some suggestions on the phone yesterday. The switch has a plug with 3 wires: white, orange, blue with black stripe. The other side has a plug with two wires, purple and grey. I tested the three wire plug with key on engine off. Here are the results with plunger in and out:
....... Orange ........ White......... blue
In ....... 12.4 V........ 0 V......... 0 V
Out....... 11.7V......... 11.7V......... 11.7 V

The two prong side of the switch for the purple and grey wires did not show voltage, no matter if the plunger was in or out. It would seem to me that with the plunger out (brake depressed) the voltage should be cut to the cruise and torque converter. So does the above make any sense?
 

v6turbo87

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Where are your meter probes when you are reading the two wire plug? And,as I said, there is a separate switch for the cruise control. Do you see a larger switch with a vacuum hose running to it near the brake switch you are working on? That is the cruise control switch. You do know you need to read voltage with one of the meters probes on ground right ?

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RmvBfrFlght

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It sounds as though someone may have been in there and swap some wires around. Looking at the drawings they have a different color for one of the TCC wires.

These wire colors and results you posted above are correct, they are for the brake lights:

Here are the results with plunger in and out:
....... Orange ........ White......... blue
In ....... 12.4 V........ 0 V......... 0 V
Out....... 11.7V......... 11.7V......... 11.7 V

Orange is +12 volts (always hot), while the white wire goes to the turn signal switch assembly and the lt blue wire goes on to the third brake light.

Now for the TCC switch, it should have a PNK/BLK wire to it that is +12 volts from the ECM/SOL fuse. With the purple wire going on to the TCC solenoid.

The gray wire is for the cruise control switch, along with a brown wire. Makes me wonder is someone was in there and swapped some terminals/wires around in the connectors.

Note that these colors are for the '86-'87 Regal, and they are from wiring diagrams, and haven't been confirmed in an actual car.

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GNRick

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Where are your meter probes when you are reading the two wire plug? And,as I said, there is a separate switch for the cruise control. Do you see a larger switch with a vacuum hose running to it near the brake switch you are working on? That is the cruise control switch. You do know you need to read voltage with one of the meters probes on ground right ?

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Yes I had the black meter wire grounded. That is how I was able to register voltage on the orange, white, and blue wires. I pressed in the brake pedal while I was checking the brake switch to see if that larger switch above it had some effect. It did not.
 

GNRick

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It sounds as though someone may have been in there and swap some wires around. Looking at the drawings they have a different color for one of the TCC wires.

These wire colors and results you posted above are correct, they are for the brake lights:

Here are the results with plunger in and out:
....... Orange ........ White......... blue
In ....... 12.4 V........ 0 V......... 0 V
Out....... 11.7V......... 11.7V......... 11.7 V

Orange is +12 volts (always hot), while the white wire goes to the turn signal switch assembly and the lt blue wire goes on to the third brake light.

Now for the TCC switch, it should have a PNK/BLK wire to it that is +12 volts from the ECM/SOL fuse. With the purple wire going on to the TCC solenoid.

The gray wire is for the cruise control switch, along with a brown wire. Makes me wonder is someone was in there and swapped some terminals/wires around in the connectors.

Note that these colors are for the '86-'87 Regal, and they are from wiring diagrams, and haven't been confirmed in an actual car.

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So are you saying my orange wire is the pink/black wire in the schematic?
 

RmvBfrFlght

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So are you saying my orange wire is the pink/black wire in the schematic?
The orange, white, and lt blue wires are all correct, don't do anything to them.

You mentioned having a connector with a gray & purple wire. I don't believe the gray wire belongs there, it should be for the cruise control switch, not the TCC switch. Look around for a pink/black wire, that should be power for the TCC switch connector. Then the purple wire goes on to the transmission connector for the solenoid.

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RmvBfrFlght

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I just recalled that I have some pictures of that area under the dash. They do verify the wires colors. Here is the brake switch:

GN_PN-SW_1.JPG


Bottom left is the brake/TCC switch. The left side connector is for the TCC solenoid, note that there are two PNK/BLK wires (+12V) and the purple wire. The right side wires in the fast-ons are for the brake lights: orange being power, with the white & lt blue going hot when the pedal is pushed.

GN_FuseBlock.jpg


In this picture the cruise control switch connector is hanging center right, light blue connector (no switch installed). Note that it has a brown and gray wire. And right above it is the brake/TCC switch, partially shown.

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GNRick

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I thought the brown wire in the blue connector goes to the transmission? And the grey wire goes to the cruise control? If not, how does the brake switch influence the cruise/torque converter when you touch the brake? That brown wire looks like the wire down at the transmission, upper left in the 4 prong plug. Could you PM me your phone #? Thanks for the help and pictures.
 

RmvBfrFlght

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What year is your car?

In the last picture I posted the light blue connector is for the cruise control switch. The wires go to the CC module.

There is a tan/black wire at the transmission, it may look brown due to age. It goes to the ECM for the ground to activate the TCC solenoid.

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GNRick

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What year is your car?

In the last picture I posted the light blue connector is for the cruise control switch. The wires go to the CC module.

There is a tan/black wire at the transmission, it may look brown due to age. It goes to the ECM for the ground to activate the TCC solenoid.

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My car is 87. Yes, the wire at the transmission under the purple wire is tan/black. The other two wires at the transmission are green and green/white I believe. The problem is, the wire at the transmission in the top left of the plug is dead. I am certain that is the same wire that goes to the brake switch. Are you sure both wires in the blue connector go to the cruise control? If so, where does the wire in the transmission (top left) go? I need to get power to that wire!
 

RmvBfrFlght

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Being an '87 it should be exactly like the pictures show. Maybe the same person that worked on my car's switches worked on yours too :wtf: Which is why there are fast-ons on the brake wires, and some heat-shrink on the purple and gray wires. It was alllllll messed up when I got the car.

Look for the PNK/BLK wires under the dash, they provide power to the TCC part of the switch. At key-on, engine-off (or on), they will be hot via the ECM/SOL fuse (10A). With the brake pedal not touched the TCC switch is closed and the transmission gets +12 volts on the purple wire to the TCC solenoid.

Depress the brake pedal and the switch opens, forcing the TCC solenoid to unlock.

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GNRick

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Ok I can look for the pink/black wire, but again, the brake switch has an orange, white, and blue wire on one side of the switch, and a grey and purple (or brown, hard to tell) wire on the other side of the switch. The two wire light blue connector looks exactly like in your picture. Is that a brown or a funky purple wire in it?
 

RmvBfrFlght

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Ok I can look for the pink/black wire, but again, the brake switch has an orange, white, and blue wire on one side of the switch,
This is OK (correct).

and a grey and purple (or brown, hard to tell) wire on the other side of the switch.
This is incorrect. Sounds like the cruise control connector is plugged in where the TCC connector needs to be plugged in. Here is another angle on the correct wiring of the Brake/TCC switch assembly (pretend the brake light wires have a housing):

GN_BrkTcc_1251.JPG


The two wire light blue connector looks exactly like in your picture. Is that a brown or a funky purple wire in it?
It is brown, a better picture:

GN_BrkTcc_1249.JPG


This connector goes onto the switch assembly that has the big vacuum hose. The CC switch assembly is only used for the CC, nothing else.

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