having an oem cruise issue

Alright all I have a tech question for you. I am working on a 2000 Tahoe and I put a remote start system on it. I am sure everyone has. Anyways the issue I have run into is the brake wire (white) at the switch shows 5 volts when the truck s on. So it shuts my remote start system down before it starts. My question is who all has run into this and what issues have you found? I have also learned that the if I unplug the cruise control under the hood then it drops to 0 volts. So I would think obviously the Cruise has an issue but again what would that issue be. Let me know if any of you have ever ran into this. Thanks and hope it is ok to have posted this.

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Let Originality Define your Individuality.

I seem to remember those trucks having faulty brake switches. You should check all brake lights are working and ground connection for cruise is good. Use a volt/ohm meter to confirm readings. The white wire at the brake switch should have a reading of less than 10 ohms resistance to ground with ignition off.

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sparky

sparkie wrote:

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I seem to remember those trucks having faulty brake switches. You should check all brake lights are working and ground connection for cruise is good. Use a volt/ohm meter to confirm readings. The white wire at the brake switch should have a reading of less than 10 ohms resistance to ground with ignition off.

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I did check the switch and even with the switch unplugged the white wire still has the 5v with the ignition on.

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Let Originality Define your Individuality.

Hi,
Put your vehicle info in on autozone.com for wiring schematics.
Autozone shows two different schematics (who knows) but trying to identify which pertains to yours. Where is the stop lamps fuse located?   Could be labeled STOP LPS (20A) underhood or STOP/HAZ (20A) at the instrument panel? If underhood, there should also be fuses labeled VEH STOP & CHMSL.
Mark

Has this Tahoe been retrofitted with LED taillights?

I looked at the wiring diagrams for the 2000 Tahoe. The white wire at the brake light switch goes through the turn sig switch to the brake light filaments. Any residual voltage from the cruise will shunt through the brake-lights to ground resulting in 0-Volts on the white wire with the pedal not depressed.

LED taillights would explain the ~5volts on white wire, coming from the cruise. Too much resistance at the taillights to shunt away the cruise residual voltage present on the white wire. If I'm correct (LED taillights), the cruise probably doesn't work either since the LED installation.

a large power resistor from the white wire to ground would fix this. But I'm not knowledgeable enough to suggest a resistor spec.

davep. wrote:

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Has this Tahoe been retrofitted with LED taillights?

I looked at the wiring diagrams for the 2000 Tahoe. The white wire at the brake light switch goes through the turn sig switch to the brake light filaments. Any residual voltage from the cruise will shunt through the brake-lights to ground resulting in 0-Volts on the white wire with the pedal not depressed.

LED taillights would explain the ~5volts on white wire, coming from the cruise. Too much resistance at the taillights to shunt away the cruise residual voltage present on the white wire. If I'm correct (LED taillights), the cruise probably doesn't work either since the LED installation.

a large power resistor from the white wire to ground would fix this. But I'm not knowledgeable enough to suggest a resistor spec.

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Yes this is in fact the issue and for now I have re installed the factory tail lights. I also do not know for sure what resistor to use. I will have to do more research. Thanks for all the help.

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Let Originality Define your Individuality.

nstlfrk wrote:

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davep. wrote:

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Has this Tahoe been retrofitted with LED taillights?

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Yes this is in fact the issue and for now I have re installed the factory tail lights.

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Thank You for the feedback.

That is one of the reasons I suggested measuring the resistance to ground on the brake circuit. Forget the resistor method. Cut the white brake light wire just after the brake switch. Connect the switch side to a relay terminal #86. Connect terminal #85 to ground. Connect the vehicle side of the cut white wire to terminal #30. Terminal #87 to the orange wire on the brake switch. Terminal #87a to ground. Or just use the original brake lights. If more than one brake light bulb is out,your cruise may not work. Don't change any wires otherthan what I mentioned for safety reasons relating to cruise control operation. The relay will make a clicking noise when the brake is applied, so bury the relay andwrap it tightly with some foam to deaden the click.

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sparky

sparkie wrote:

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That is one of the reasons I suggested measuring the resistance to ground on the brake circuit. Forget the resistor method. Cut the white brake light wire just after the brake switch. Connect the switch side to a relay terminal #86. Connect terminal #85 to ground. Connect the vehicle side of the cut white wire to terminal #30. Terminal #87 to the orange wire on the brake switch. Terminal #87a to ground. Or just use the original brake lights. If more than one brake light bulb is out,your cruise may not work. Don't change any wires otherthan what I mentioned for safety reasons relating to cruise control operation. The relay will make a clicking noise when the brake is applied, so bury the relay andwrap it tightly with some foam to deaden the click.

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I can still measure the ground resistance ad am planing to tomorrow. But the relay idea I was gonna try but it would only fix the remote start issue and not the cruise issue. I would rather not add a relay where it is not needed. I plan on getting the resistance correct and using this at the lights. From what I have read on the internet it seems to be very simple I just have never ran into this issue due to I do not usually install LED lights on vehicles.

Thanks for all the help everyone I really appreciate it.

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Let Originality Define your Individuality.

Adding the relay will fix the cruise as well. Adding resistors in the manner described is not advisable. This same fix is used for many vehicles and is safe. I have used it many times. If you don't want to then scrap the LED tail lights and all should be fine as long as they work.

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sparky