Door locks inop (but FOBs work)

'98 Transport Montana, 75k miles, V6 engine, standard stuff plus power slider. No extra non-factory stuff like car starters or security systems. All fuses are visibly not-blown, but relays could always be suspects since they all look OK regardless...

Strange as it may sound, but there are a few other strange items I have noticed also. I just got the van back from my ex, and WHO KNOWS what has happened to it during the "dark ages"...

1. Door locks don't function AT ALL. Only manual operation, and FOBs work.

2. Window switches don't work, except pass side switch seems to try to move the window UP, but not down. Dr side switches do NOTHING.

3. When parked, key off (but in ignition, off position), doors closed, the interior lights and map lights occassionally flicker on and off.

My first idea was blown fuses or stuff, but everything there seems OK. Then, when I found the "window tries to go up but not down" thing I started thinking it's a BCM problem...

Help!? :banghead:
TIA,
Tom

I fixed my door locks just three days ago. On my car (1999 Transsport) The door locks would unlock with the switch on the door, but they would not lock. The fobs worked fine. The problem is in the wiring. here is how to fix it. On the passenger side of the car the wiring runs under the carpet beside the door sill. Pry up the door sill and lift the carpet. Under the carpet is a wire bundle. The wires you are looking for are light blue (lock) and white(unlock). You will have to remove the black tape from around the wire bundle. Look for the spot where two wires chane to one. This is the splice to bring the wire from the two doors down to one wire that goes into the BCM. On my car this splice had corroded and broken. Splice the wires back together again and it should fis the problem with the door locks. I have not had the same problem with the windows but the next time I have the wiring diagram out I will see if I can find anything. Good Luck!!

i have a similar problem but its window up/down button. The drivers button for the passengers window will go down but you cant get it to go back up unless you press the passenger window up button. And it started this some time this past week.

Pry off the door lock switch panels on both doors and check for continuity (use and ohm meter) between the drivers switch for the right window, and the switch on the passenger door. The light blue wire should have continuity between each switch and the tan wire should have continuity. If they don't your problem is a broken wire somewhere in between. Good luck!

i pulled the switch panel on the drivers door. Seems that the switch itself maybe going out. It works but i got to wiggle the switch a little.

Well, you guys were right! In the middle of the bundle, there were 2 splices, one light blue and one white, both were corroded. There had been som much water corrosion, the wire literally fell apart in my hands, so I needed to splice in about 4" back from both ends with new wire. Soldered and heatshrunk both, now locks work great!

As for the windows, it look like it is the driver's side switch. I have not replaced it yet, but I noticed it was a bit cruncy. According to the manual, either the light blue or tan wire should chage from ground to +12Vdc when the switch is activated. The tan seemed to switch, but nothing with light blue, and nothing with EITHER of the driver output wires, dk brown or dr blue. lt brown (not tan) is hot input at the door, and it was hot, and the black wire (ground) seemed OK too. When I tried to take the switch apart to investigate, it pretty much disintegrated in my hands. There were several signs of overload and arcing inside the switch, and a lot of melted plastic... I guess I am just glad it wasn't a fire...

Only reason I didn't get a new switch yet, seems GM dealers aren't open AT ALL on the weekends in Michigan... What a crock... Seems like they must just make too much money.

I found some more problem splices under the carpet behind the driver seat, but that update will be posted in the other thread.

Thanks for everybody's help!
Tom

I fixed my door locks just three days ago. On my car (1999 Transsport) The door locks would unlock with the switch on the door, but they would not lock. The fobs worked fine. The problem is in the wiring. here is how to fix it. On the passenger side of the car the wiring runs under the carpet beside the door sill. Pry up the door sill and lift the carpet. Under the carpet is a wire bundle. The wires you are looking for are light blue (lock) and white(unlock). You will have to remove the black tape from around the wire bundle. Look for the spot where two wires chane to one. This is the splice to bring the wire from the two doors down to one wire that goes into the BCM. On my car this splice had corroded and broken. Splice the wires back together again and it should fis the problem with the door locks. I have not had the same problem with the windows but the next time I have the wiring diagram out I will see if I can find anything. Good Luck!!



That is exactly what my son and I did and it worked perfectly. I have a question I wonder if you know what the big whiteish, yellowish approx. 12 ga. wire 2 into 1 splice does, it was corroded and I had to fix it as well. Also what is an Fobs

Door lock problems with my 1999 Montana, will try what has been mentioned with the wires. Thanks for the advice.
I was also wondering what the FOB was.

Thanks Airmech
I had the same problem on my 2001 Montana I posted my problem But no one answered.
I did what you said and sure enough worked like a charm !!!
thanks again for the advice!!:)

My thanks to airmech. I found the corroded connection just as indicated; problem fixed. (It was the white wires that were corroded. The light blue ones were ok.)