Door locks intermittent operation
Looking for advice...
Customer states door lock operation intermittent. Upon inspection found passenger doors to not operate when commanded by remote, master switch, passenger switch or manually locking/unlocking with key in lock cylinder. Smart lock not functional either.
Driver door had a few hiccups using the remote. Seemed to be affected after Using the key in lock cylinder to lock/unlock. May have been a circuit overload protection, not sure.
No other problems noticed as far as lights, mirrors, radio etc.
Using autel scanner, I am able to see 10 modules and communicate with all. Instrument cluster has B1875 and U1262. I did Not have my scope handy to check scp data line. All data inputs appear to be in good working order. All doors register ajar or closed. Switches all show working. Windows good. Horn chirps when alarm is armed. key remote shows good programming. Only one remote programmed. 3 keys programmed and I only have access to one.
I check signals to driver door lock. I see changes. Look good. I move towards driver rear. I see changes, looks good but still no operation. I go to REM. Follow the pinpoint, looks good.
I did not get to check the FEM but from what I can tell it only looks for door ajar/closed. And scanner shows good data.
Im not sure I’ll be able to put my scope on this car. But it kicked my butt today and honestly I couldn’t figure it out. Maybe the customer will leave it maybe not. If anyone has and info I’d appreciate it. Sorry about these bad pictures of paper diagrams lol. Thanks guys I love this community
What were the results of the REM on demand test?
Can you command the door locks with the scan tool?
I don’t believe this autel has a REM test. No the locks don’t work when commanded
Seeing that it's intermittent, I would start with opening the door jamb harness and pull on each wire to see if a wire will break.
In the scan data, is the lock relay working
Can you describe the B1875 and the U1262. I guess the codes are intermittent?
U1262-SCP communication bus fault. Found in cluster but these locks do use it
B1875 Turn signal/hazard switch circuit fault. Turn signal and hazards operate normally when commanded. And when pats is armed.
I did not see lock relay. I do hear DDM, REM both working when asked and see signals coming out And reaching door latches.
My understanding is that the DDM recieves the command and then sends it down the line to FEM and REM. I’m really wanting to look at the bus line but my scope is not handy currently.
Pats has crossed my mind but there is no indication of an issue on the scanner or through any other action or visually on cluster.
Appreciate it guys
Pats will have absolutely no effect on door locks. Pats is only used to allow/disallow engine start up.
The driver door lock function is controlled by the driver door module (DDM).
The passenger door locks and the luggage compartment lid actuator functions are controlled by the REM.
The passenger lock/unlock actuators are hard wired to the REM.
Are the R/F L/R R/R doors all faulty and the driver's door works ok??
Yes this morning the driver is working properly. Tho before it was intermitt working. The passenger door do not work at all. I did pinpoint test for that symptom on the rem and all showed good. So I went to the LR door latch to check for signal. Motor wires were both normally 0v and depending on lock or unlock either wire would be switched to battery voltage. But still not working
if you have power and ground during activation, I would verify with a light bulb, but seems related to door lock actuator failure. Have you bench tested the actuator? These have integrated switches and actuators in the latched, but are not solid state. You should be able to apply power and ground and make them activate
I am going to use the bulb. I will try to manually operate the actuators. Thank you for this help. I’ll be in touch soon
In conclusion guys. I went to all the passenger latches. Checked for signals. Used a test light with t pins for the bulb check. applied the power probe. Everything led to faulty actuator.
This is a new car purchase so no history. Three bad actuators was hard for me to understand at first and make the call. So I presented it like this to my service manager.
We have three bad actuators. I don’t know if this is due to age or if something killed them.
We will see what the customer decides. Thanks so much guys. This is a really great community
recently at the shop I had a acura crv style and all actuactor were inop, I was chasing a ghost thinking there has to be some thing in common for all of then being inop, when I tested at each door the was the power and ground command both ways lock/ unlock. we call the customer and she said one by one was failing litlle by little and when the driver side failed she brought it to the shop , I did not get this info from the service writter , A lot wasted time