dville_gt

iTrader: (5)

Low beams stopped working. Light sensor is still working as when I command them off the DIC reads "headlamps suggested". Tail lamps/running lamps come on as well, just doesn't fire up the HID low beams. Went through the procedures to check the control circuit and relay, but I believe the problem might be within the fuse box itself.

The control circuit wire should drop ground to the M2 prong of the low beam relay in order to activate the low beams. If I check continuity on the wire when it should be grounded it goes back and fourth from no continuity to showing some continuity and back. If I jump that prong of the relay straight to ground the HID's come right on as they should.

I pulled the fuse panel apart and found that I have continuity between M2 (relay 47) on the top side of the fuse panel and both pin F1 of connector C3 and pin B1 of connector C1. I don't know which of these are the correct wire and/or why they are somehow internally connected. That is the only other pin that F1 has continuity with.

If anyone could pull up the underhood fuse/relay wiring diagram it would be a huge help. Once I know a: if these wires should be connected, and b: which one is the correct wire, I can decide if the problem is the fuse box itself, the BCM or the wiring between.

Thanks.

TEXASLESS

2008 Chevrolet Corvette | Document ID: 1894197
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WIPER, W/S WASH, LT HI BM, RT HI BM, LT LO BM, RT LO BM, WPR DWELL, WPR/WSW Fuses, and HIGH BEAM, LOW BEAM, WIPER RUN/ACC, WIPER ON/OFF, WIPER HI/LO Relays

dville_gt

iTrader: (5)

Okay. I found this, but it doesn't seem to explain why I am getting continuity between F1 on the C3 side of the fuse panel and B1 on the C1 side of the connector. According to this diagram that I found on a "freebie" alldata type site, the ground either comes from the BCM or it comes directly from the turn signal stalk (multi-function switch). But either way they both look to come together BEFORE pin F1. I looked through a bunch of diagrams and cannot seem to find what B1 in the C1 connector is.

dville_gt

iTrader: (5)

here is the complete diagram for the head lights. after examining it further it seems the body control module is in charge of firing up the head lights both on auto or if you manually turn them on. if on auto it uses the sun sensor through the serial data link into the bcm (yellow line), if on manual it should use pin 15 (blue line) to tell the bcm to force the lights on. what was throwing me off was the green line, however i believe that is used for the "flash to pass" feature. not exactly sure what the wiring diagram is showing there, but it looks like it is used to determine if it is flash to pass or high beams (i am not sure on this however). still have no idea why pin b1 on connector c1 is internally connect to f1 on c3 however since i don't know what b1 on c1 is.

ramairracer

iTrader: (13)

i couldnt really understand what all youve done,
but i would start with checking power and ground at the light or ballast if you dont have any power go back to the relay (47 low beam) and check you should have battery voltage a two pins and ground on one with lights off, that if the realy works will then be batt power.
The other termianl will be grounded by the bcm so keep either a meter or test light to voltage and see if it grounds when you manually turn on the lights

dville_gt

iTrader: (5)

according to a buddy:

interesting. this is making me believe the problem must be the body control module. i'll check it when i get home. if i apply ground to pin 15 on the C2 BCM connector it should ground pin 3 on the c2 BCM connector which should ground pin F1 on the C3 fuse box connector which should ground pin M2 on relay 47. otherwise i'll check and see if pin 15 is getting a ground signal from the multifunction switch in the first place.

dville_gt

iTrader: (5)

the problem is somewhere between the multi-function switch - bcm - and fuse panel. if i manually ground pin m2 on relay 47 (thus triggering the low beam relay) the head lights fire up normally. the problem is that the car is not grounding that relay on it's own either due to a problem within the fuse box, a problem with the bcm not dropping ground to it, or a (rather unlikely) problem with the actual turn signal stalk not telling the bcm what to do (unlikely since the display reads "headlights suggested" when i have it in lights in the off position and it is dark outside).

dville_gt

iTrader: (5)

this should be bcm c2 that should tell the story.

dville_gt

iTrader: (5)

ended up being the circuit 1970 wire (pink/white) between the bcm and underhood fusebox had no continuity.