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My 2001 V70 T5 just suffered failure of several rear components all at once. I can't find anything obvious in any visible wiring or fuses (all fuses have been checked and are fine) but there is definitely something broken somewhere. Here's the list of things not working:
Fuel Level Sensor
Reverse Lights
Rear Wiper & Washer Pump
Rear Hatch Lock
Rear Door Locks
Fuel Door Lock
All other rear lights and electronics seem to work fine. Door sensors work fine but locks don't. The fuel guage reads empty and the trip computer won't show the remaining miles until empty. The alarm goes off if I lock doors with the remote and open the rear hatch, but the alarm does NOT go off if I open a rear door.
Has anybody experienced this or have suggestions of what to look for? I'd rather not spend money to diagnose this unless absolutely necessary.
Unless this is really an old Plymouth named "Christine", I'd be thinking that some ground which is a common ground has come loose. Without a wiring diagram, however, this is just a guess. All of those connections can't have gone bad at exactly the same time by sheer chance. I'd try to see if the grounds were working first. I doubt that these components share any common relay, and with good fuses you know there's no massive short. Probably the easiest to test is one at a light bulb socket.
Good luck And I hope you get a more knowledgeable answer from some electrical components wizard.
CAN, CAN, CAN...It's great until it doesn't work. Your car has an extensive data network running throughout called CANbus. CAN=controller area network ...bus =serial data bus.
From the diagrams in Haynes there is a rear electronic control unit that might have a problem receiving CAN serial data or an . This module drives all of the relay coils that operate the function you mentioned. It's not easy to troubleshoot. There is a microprocessor in this module and any of a multitude of things could affect it. I don't know where it is but I'm sure I'll find out sometime... we also have a 01 V70. If you find it check the wiring(especially the wires going into A14 and A16 they are the CAN serial bus wires) , unplug 1 relay at a time and test. These are though problems.
Also, just a heads up, we had a problem with our AC control. The temperature control ***** where not being sensed by the CAN controller. After an hour of looking for a mechanical problem(ie gas and compressor) I knew it had to be a control issue so in disgust I just turned the temperature ***** up to full heat and then down to cold and Bingo nice cold air, just like that. So now when it feels like it's getting warm we just turn the ***** up and down and it cools.
Both suggestions are helpful, thank you. I'll research the canbus. I'll keep you posted on what happens, but if anybody has any pointers I still have my ears open.
Best,
Ken
All problems associated with the rear electronic module (as mentioned on the other forum) and I have some other questions to help determine the problem.
Do the brake lights work? All of them, L, R upper? I wouldn't expect the brake lights to work if the REM is completely dead. I believe the tail lights and license plate lights work because they're controlled by the central electronic module but not the brake lights.
When the alarm is activated is it both rear doors that won't set it off if either are open, did you try both doors? This is a good observation and doesn't make sense if the tailgate sets off the alarm but the rear doors do not. This is controlled by the central electronic module. Need to know if you see this problem with both rear doors.
Are these problems intermittent, do things start working again sometimes, do the problems start and stop working all together?
Good questions. After more testing the rear doors DO set off the alarm. When I checked before I didn't wait long enough for the alarm to arm. So, all doors that don't lock will trigger the alarm when opened.
All brake lights, turn signals, and running lights work except the rear fog light. It doesn't appear to work either. I hadn't checked that before.
None of this is intermittent. It's been this way since the original failure.
Would connections be loose or is the module or relays likely bad?
Thank you, and I greatly appreciate the input.
Best,
Ken
Good news! (I think) Because the diagrams I'm looking at show that brake lights , turn signals, tail lights are all controlled from the rear controller. So this means you are receiving CAN messages and the serial bus is A OKAY. The fuel level sender? I can't see it in my diagrams. I'd start looking at the relays. I only see one power source to the rear controller and it must be good if other things are working.
The real strange thing is the limit switches that sense the doors locked or unlocked are wired directly to the central controller. Go figure?? the limit switches aren't the problem because the doors aren't locking.
Your REM is not communicating with the rest of the car. I would suggest a power down, power up cycle by disconnecting and reconnecting the battery. See the links below for a similar issue and the battery disconnect, reconnect procedure.
I looked at the wiring diagram again and the reason your brake lights still work (when most other REM functions don't) is due to a direct signal from the CEM to the REM for the brake lights. Most other REM functions, the ones not working, are done over the CAN bus as Bobec mentioned and it appears there's no communication over this bus with the rest of the car.
A power cycle may reset the REM electronics, it's worth a try. One other thing I would do while the battery is disconnected is just swap out the two 10amp fuses that supply power to the REM with other 10amps fuses in the module. Fuses 11/D1 and 11/D2 are the REM power fuses and they are the top two fuses in the left column. Swap those with other 10amp fuses.
When reconnecting the battery make sure the ignition switch is position II (as describe in the linked procedure), in my opinion this does a better job of bringing up all the electronic module signals at the same time.
Doug, you just saved me a bunch of money. I can't thank you enough. I disconnected the battery per the instructions you linked and everything works. I've got a working gas guage again, the doors and hatch lock and unlock, the rear wiper wipes and the washer pump pumps, reverse lights light, it all works!
Thank you, thank you, thank you!
I love this forum!!!! I hope to be able to provide information to someone else that is as useful as this was to me.
Again, I can't thank all of you enough for taking the time to read this, think about it, research it, and respond.
This is good news Ken and with power cycling clearing up the problem it means it was likely a latch-up condition with one of the electronic devices in the REM. Power has to be removed completely to clear up a latch-up conditoin.
Wow, this is great advice. I had this EXACT problem. The local mechanic, not a Volvo specialist, could not sort it and I was headed for the Volvo dealer or independent specialist. Instead, I looked online and found this thread.
Using Howard's procedure for dis/re-connecting the battery, it worked!
I can't thank you enough, Howard (but I'll do it anyway). Thanks so much!
Hi I just joined the forum because of this thread!
I have a 2004 V70. I just had the dealer replace fuel rail pressure sensor and fuel pump due to error codes. Now the right rear tail light and right fog light don't work. Brake lights work, backup lights work, I think the both blinkers work too. The mechanic is saying I need to replace the rear lighting control module REM. I'm not sure what he's basing this on. Will the batter disconnect procedure help?
Thanks!
Now the right rear tail light and right fog light don't work.
There are 2 taillamp bulbs (5 watt parking lights) in each side on the rear - do both not work on the right? Those are fed power from a shunt - have you tried swapping the left and right shunts? I trust the right front parking light works - fuse 31 powers both the right front and rear parking lights. Many Volvos only have a fog light on one side - the left side for lhd cars. Note the fog lamp is in a dual filament 5/21 watt bulb with the 5 watt filament being the middle parking light. Are you certain you have/had a right rear fog lamp?
11-10-2009, 11:56 AM
2001 V70 T5 Multiple sudden rear electrical failures
