rindone80 Posted June 27, 2006 Report Share Posted June 27, 2006 I have a '93 Cadillac Allante and I'm fighting a headlight problem. The low beams don't turn on, though the high beams work. Everything else works as it should, including the twilight sentinel which dims the cabin lights & apparently sends out the signal to to the BCM to turn the low beams on. I took the car to Cadillac and they said to replace the BCM & headlight control module... Replaced both of these but no luck. Since then, I replaced the bulbs just to be safe. I got my hands on a couple old Allante relays and have been swapping them out at random but so far with no luck. I swapped relays in both the battery compartment and in the front behind the passenger side headlight. All fuses & relays appear to be fine. This includes the MAXI fuses. I believe I may have a wiring problem. I bought a multimeter yesterday to test continuity but am unsure what to look for. I've ordered a shop manual with the electrical schematics. For fun I did a little research on the internet & found instructions on how to reset the fault codes on the Driver Information Center (DIC) I reset all codes this evening and will drive the car tomorrow to see if it generates any faults over the course of the day. *Is there a way to test the relays? *Is there a way to verify continuity from point to point? *Is there a way to verify a signal is being sent from the headlight control module to the BCM to the relay? (I'd like to test the BCM just to be sure) What would you suggest doing, besides asking Cadillac in St. Pete for a refund for the wrong diagnosis? Appreciate any ideas! - Ryan Link to comment Share on other sites More sharing options...
Dan Posted June 27, 2006 Report Share Posted June 27, 2006 Could possibly be a problem with the dimmer switch, or a wiring problem in the steering column. Or it could be as simple as a bad fuse. Those are the places I would check first. Link to comment Share on other sites More sharing options...
rindone80 Posted June 27, 2006 Author Report Share Posted June 27, 2006 Could possibly be a problem with the dimmer switch, or a wiring problem in the steering column. Or it could be as simple as a bad fuse. Those are the places I would check first. Dan - I can safely say that it's not a fuse. What I didn't volunteer in the last message was I drove it home one day during a violent Florida rainstorm and at one point had to drive through about 8+ inches of standing water. I think it was at this point that my headlights quit. - Ryan Link to comment Share on other sites More sharing options...
Dan Posted June 27, 2006 Report Share Posted June 27, 2006 Based on what you said about the water, it almost has to be a fuse or relay. This is probably a long shot, but I would also check the grounds to the battery, and to the headlignt, that if you have a ground to the headligt in your car. Link to comment Share on other sites More sharing options...
rindone80 Posted June 27, 2006 Author Report Share Posted June 27, 2006 Based on what you said about the water, it almost has to be a fuse or relay. This is probably a long shot, but I would also check the grounds to the battery, and to the headlignt, that if you have a ground to the headligt in your car. Dan - I assume the grounds to the battery are the same for the brights & the low beam. That being the case I'd say the ground wire is OK since my high beams work. Even so - I'll check the grounds out once I get ahold of my very own Allante shop manual. Every Allante should have been sold with a shop manual! Do you see the relay and/or water issue as possibly having shorted out my BCM or headlight control module? Having replaced the BCM & headlight control module already and then pulling them out after seeing no result, I'm wondering if I may have been too quick to pull these out before swapping relays. I reset all the DIC codes last night & drove the car today. When I got home tonight I cycled the twilight sentinel by putting a shade over the light sensor to turn the light system on & off a few times. I rechecked the DIC for new codes and found none. I did, however, take note of the historical codes before clearing them out of the DIC. If it would help, I can write these codes in my next message with their abbreviated fault descriptions. Link to comment Share on other sites More sharing options...
Dan Posted June 28, 2006 Report Share Posted June 28, 2006 I don't know about your Allante, but the owners manual for my car lists what fuse and relay does what. Look for the ones that control the low beams. I suspected a fuse because when the water connected the negitive and postive currents at the headlight, the fuse would blow to protect the circuit. Usually when you lose high or low beams in both headlights, its a dimmer switch problem. Try switching from high to low beam repeatedly, the switch might be stuck. A easy way to test relays is to switch with a relay that you know works, like a turn signal or horn relay. If you switch relays and your turn signal works, then you know the relay is good. Link to comment Share on other sites More sharing options...
rindone80 Posted June 28, 2006 Author Report Share Posted June 28, 2006 I don't know about your Allante, but the owners manual for my car lists what fuse and relay does what. Look for the ones that control the low beams. I suspected a fuse because when the water connected the negitive and postive currents at the headlight, the fuse would blow to protect the circuit. Usually when you lose high or low beams in both headlights, its a dimmer switch problem. Try switching from high to low beam repeatedly, the switch might be stuck. A easy way to test relays is to switch with a relay that you know works, like a turn signal or horn relay. If you switch relays and your turn signal works, then you know the relay is good. Dan - I just read in the manual about the headlight switch having a circuit breaker which will trip in the event of a short. Is this breaker resettable? Link to comment Share on other sites More sharing options...
Dan Posted June 28, 2006 Report Share Posted June 28, 2006 I honestly don't know about the circuit breaker in the headlight switch. Just a thought, have you tried removing the connectors to the BCM ,and headlights, and drying them out. If there is still water in there it might be causing problems. Also make sure the relay/fuse box is dry too. Link to comment Share on other sites More sharing options...
rindone80 Posted June 28, 2006 Author Report Share Posted June 28, 2006 I honestly don't know about the circuit breaker in the headlight switch. Just a thought, have you tried removing the connectors to the BCM ,and headlights, and drying them out. If there is still water in there it might be causing problems. Also make sure the relay/fuse box is dry too. Already replaced the BCM, headlight switch. That didn't help me. The connectors are in great shape. I had the whole console apart and can see that it was never wet. The interior was never wet or anything.. it was just standing water I drove through. The fusebox behind the headlights probably got doused with all the water kick-up from driving. That fuse box and the possible headlight switch breaker is what my money is on. Shop manual should be in tomorrow. My grandfather has a great mechanic down in Sarasota who works on Caddys so I might drive down there this weekend and leave the car with him. Link to comment Share on other sites More sharing options...
Bill K Posted June 29, 2006 Report Share Posted June 29, 2006 If you have the "flash to pass" type turn signal/birght-dim switch and the low beams work when the switch is pulled back it may be a faulty switch. I've had this problem on another car (not Cad). Link to comment Share on other sites More sharing options...
johnnydone Posted June 29, 2006 Report Share Posted June 29, 2006 YOU MIGHT TRY DICK HUSSEY http://www.allantesource.com/ Link to comment Share on other sites More sharing options...
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