SierraIndiaTango
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- Joined
- May 7, 2012
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Greetings,
I have recently purchased a 94 Z71, got it for $800 with some problems, most of the problems are being worked out, but one has stumped me completely
the truck had a trailer brake installed under the steering column, tied into a yellow wire under the dash and had 3 wires entering the engine bay, black-blue-white, they were already cut when we got the truck so I have no idea where they went, somewhere on the passenger side of the engine bay, i think to the far left empty stud on the junction box, at first the brake lights would not work at all but everything else did, we discovered the yellow wire that had a "quick splice" type connector was broken inside, so we rewired the yellow wire back together and had functioning brake lights, however once we turned the ignition on, no brake lights
we checked all the fuses, and then got confused a bit since the "HTR A/C" fuse lights up with the light tester, which of course makes the A/C display come on I guess, the 4WD fuse also lights up when you press the brake pedal.. does not seem like these fuses should be doing anything with the ignition off
when you press the brake, the relay also does something weird , with the ignition off the brake relay has no hot wires, when you press the brake the 2 yellow wires light up hot and the relay clicks, I believe this is how its suppose to work? the other 2 wires do nothing (cant recall what color they are at the moment), however when you turn the ignition on, the yellow wires are hot but very dim(led test light) when you press the brake pedal they light up brighter but the relay does not click and the brake lights will not come on, there is also a third wire on the relay that is hot all the time with the ignition on, if you take the cover off the relay and physically push the relay, the tail lights come on like normal
I tried a known working relay from my other truck and it still does the same thing, ignition off, no hot wires on the relay until you press the brake pedal(2 yellow wires light up) ignition ON and the 2 yellow wires are dim but get bright if you press the brake pedal (brake lights do not work) and a third wire is hot at all times as far as I know, fourth wire is never hot on the relay as far as I know
another possibly unrelated oddity is the PCM or ECU whatever, its loose behind the glovebox and I assumed it should be mounted securely ?, it also has the wire soldered with a small block of stuff, taped up with tons of electrical tape, which is grounded with a wire to the top of the PCM, its soldered into the number 10 wire on the blue plug I believe, pink with a black stripe, no idea if this could be related?
thanks in advance for any help, I can attempt to provide more information if need be, I just have no idea where to go from this point
I have recently purchased a 94 Z71, got it for $800 with some problems, most of the problems are being worked out, but one has stumped me completely
the truck had a trailer brake installed under the steering column, tied into a yellow wire under the dash and had 3 wires entering the engine bay, black-blue-white, they were already cut when we got the truck so I have no idea where they went, somewhere on the passenger side of the engine bay, i think to the far left empty stud on the junction box, at first the brake lights would not work at all but everything else did, we discovered the yellow wire that had a "quick splice" type connector was broken inside, so we rewired the yellow wire back together and had functioning brake lights, however once we turned the ignition on, no brake lights
we checked all the fuses, and then got confused a bit since the "HTR A/C" fuse lights up with the light tester, which of course makes the A/C display come on I guess, the 4WD fuse also lights up when you press the brake pedal.. does not seem like these fuses should be doing anything with the ignition off
when you press the brake, the relay also does something weird , with the ignition off the brake relay has no hot wires, when you press the brake the 2 yellow wires light up hot and the relay clicks, I believe this is how its suppose to work? the other 2 wires do nothing (cant recall what color they are at the moment), however when you turn the ignition on, the yellow wires are hot but very dim(led test light) when you press the brake pedal they light up brighter but the relay does not click and the brake lights will not come on, there is also a third wire on the relay that is hot all the time with the ignition on, if you take the cover off the relay and physically push the relay, the tail lights come on like normal
I tried a known working relay from my other truck and it still does the same thing, ignition off, no hot wires on the relay until you press the brake pedal(2 yellow wires light up) ignition ON and the 2 yellow wires are dim but get bright if you press the brake pedal (brake lights do not work) and a third wire is hot at all times as far as I know, fourth wire is never hot on the relay as far as I know
another possibly unrelated oddity is the PCM or ECU whatever, its loose behind the glovebox and I assumed it should be mounted securely ?, it also has the wire soldered with a small block of stuff, taped up with tons of electrical tape, which is grounded with a wire to the top of the PCM, its soldered into the number 10 wire on the blue plug I believe, pink with a black stripe, no idea if this could be related?
thanks in advance for any help, I can attempt to provide more information if need be, I just have no idea where to go from this point