Edmunds Answers



  • zaken1 03/13/10 11:33 pm PST

    Gee whiz; it sure would have been simpler if the installer had run power for the CHMSL directly from the existing CHMSL on the truck. Then it would have worked as it is intended to. Using the brake light power for a chmsl, on a vehicle with bulbs that are shared by the brake lights and blinkers is not appropriate; because each brake light cuts off when the blinker on that side is activated. The installer messed up. If the stop-logic module really works; you might be able to fix this by removing the ground wire that was run to the left signal; and instead running that wire to a grounded point that is independent of the rear lights. If there was a loose connection or even a small resistance between the left rear light assembly and ground; it would have caused this problem.

    You can determine whether the grounds are switched or not, by simply tracing the ground wire from the rear light assemblies. If it goes to a ground bolt in the body; then the grounds are not switched. Switching grounds would require separate ground wires from each side going all the way back to the turn signal switch. I would never expect GM to spend money on something like that when it didn't have to. A resistive ground connection on your old 2000 Silverado may have produced a false voltage reading on the ground side of the headlights, which led you to mistakenly conclude that the power was being switched on the ground side. But I didn't come here to argue; only to help make your lights work.

  • patriot9 03/14/10 9:37 am PST

    Thanks for the responce.

    I think I will poke around today and find a better way to get the chmsl to work. I will test my theory about switching the grounds and post results.
    Just FYI. The StopLogic modual is supose to function as follows...

    There are three terminals labled R/T, L/T and Stop.
    With power applied to BOTH R/T and L/T, Stop wil have power.
    With power applied to R/T OR L/T, Stop will have no power.
    With power to BOTH R/T and L/T but modulated at one to simulate a turn, stop will have power.

    Thanks for confirming my thoughts that the installers did it wrong.


Top Chevrolet Silverado 1500 Experts View More

Rank Leader Points
1. karjunkie 840
2. MrShift@Edmunds 545
3. zaken1 310
4. obyone 250
5. docj 240
6. 0patience 190
7. morin2 135