relay issues?

larryizacat

Original poster
Member
Jul 3, 2012
5
I recently had to replace the fusebox in my 04 trailblazer due to the 46 hdm relay shorting and completely burning through the old box. Everything now works except the low beams. All relays and fuses work, connections are good, new bulbs, even tried a new bcm, and nothing. On a whim i touched the #5 pin on the hdm relay with a 12 volt test light while it was slightly lifted out of the fuse box, and the lights came on, and turned off andon with the switch. Any ideas where i go from here?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
That relay is fed from the PCM, with a PWM signal to handle the DRL function. Might be the PCM driver is damaged, or the wiring. Check continuity from the relay control back to the PCM. Assume you have the schematics from here or you have your own AlldataDIY subscription?
 

larryizacat

Original poster
Member
Jul 3, 2012
5
honestly, its been alot of guesswork. Used the burnt 04 box as a model to rewire the new box which is an 05. Have no schematics on hand. Was just shocked to see the lights go on when i grounded the #5 pin in the hdm, seeing how the new bcm did nothing. haven't looked into the pcm as of yet since the bcm supposedly sends the signal to the 5. should i bother with a pcm relearn or just go straight for wiring?

- - - Updated - - -

honestly, its been alot of guesswork. Used the burnt 04 box as a model to rewire the new box which is an 05. Have no schematics on hand. Was just shocked to see the lights go on when i grounded the #5 pin in the hdm, seeing how the new bcm did nothing. haven't looked into the pcm as of yet since the bcm supposedly sends the signal to the 5. should i bother with a pcm relearn or just go straight for wiring?
 

Forum Statistics

Threads
23,488
Posts
639,901
Members
18,722
Latest member
Mmc0229

Members Online