flyingAMT

08 Uplander. RH blinker flashes fast, as if bulb is burnt out. Bulbs are all fine. RH Read did not illuminate, Checked fine with meter, but replaced with a new one anyway, same problem. Tried to locate a Flasher Relay, no luck. Other threads state that Uplander doesn't use a flasher relay, but relies on BCM. The Flasher "noise" comes from the instrument cluster. Someone stated to reset BCM. I disconnected the Neg batt terminal for 30+ minutes, problem persists.

RH front turn signal light works, as do both Front and Rear on the LH side.

Hazards blink normally, but the RH rear bulb does not illuminate on flash, only tail light.

I've checked fuses, can't find one specifically for tail lights or blinkers.

This happened after pulling a small trailer. The Trailer Lights burnt out on the way home one evening, both Stop/tail and marker on the RH side.

flyingAMT

UPDATE,
There is not power (less than 1 Volt) getting to the bulb socket for the rear turn signal. I've checked the wire at every point I can reach, no voltage with the blinker flashing, so definitely not a bulb problem. I'm thinking it is a bad flasher, but still cant determine where the flasher is.

U.Nanimous

Isn't that a dual filament bulb, in which case the fact that it illuminates for "tail light" is irrelevant? The fact that this happened while towing a trailer makes it sound like something burnt out, perhaps even the wire itself.

'05 Venture myself so not sure how identical they are and I don't know how the wire gets from the front to the back anyway, but there are lots of threads (Venture forum) with electrical problems (door lock, windows, mirrors) caused by the wire bundle under the carpet at the front passenger seat. If you can get a diagram you can unplug the wire from the front and hook a battery directly to it and see if you get voltage at the bulb.

Papa Bear

I believe the "flasher" is the body computer.

This is probably not a DIY project ....
and when it's fixed it's likely a great situation for a powered T-One controller so this doesn't happen again.

U.Nanimous

If you are going to try the BCM, best way to do it would be to find an identically equipped Uplander at a junkyard and use that BCM.

tech2

your first post is correct, the system is bcm controlled, there is no flasher.




the bcm uses high side drivers to power the system. if they sense to much load they will shut down to protect from overload.


is the trailer spliced in using the factory blunt cut wiring harness?


go to the bcm, unplug the x2 connector from the bcm and power the connector(not the bcm pin) pin 48 dark green 2 wires...what happens?

flyingAMT

I'm told by a certified GM mechanic that a salvage BCM will not work. The BCM has to be programmed for the vehicle, and it's a one time thing. The odometer and VIN are programmed into the bcm along with other vehicle specific info. What's your experience with salvage bcms?

flyingAMT

Wiring is fine. Had to replace the BCM, it had multiple faults and I was told they are not repairable. I got a "favor" called in and a new BCM cost me $250, not including labor...it might be a good idea to install some fuses in the trailer wiring harness to protect the BCM from possible faults or short circuits. I can't find anything on the trailer wiring, quick is only 2 years old that would account for the BCM being overloaded. It's a small trailer with a single set of stop/tail lights. So should be well within the 7amp max per side.

tech2

plug it in and the flasher will probably work. ideally, it should be programmed to match the build and vin of your vehicle. you can take it and have the used bcm programmed to your vin by a dealer. the problem is the theft deterrent system....the bcm is the gateway module between the pcm and vehicle theft deterrent module. if it won't crank or starts and stalls...you need programming.

I have done this when I worked for gm.

U.Nanimous

None with an Uplander or even my Venture (knocking on wood), but on my '00 Impala...actually I made the mistake of letting the dealership do it anyway. For the 7th gen Impala I read enough to know it does work but there are certain programming bits that the vehicle may work fine just not the same. The big part of that on the Impala is the settings you access through the stock radio but that isn't on the Venture so I'd assume it also isn't on the Uplander.

Of course it seems I'm a little late to reply, looks like tech2 has your back - he knows his stuff.