2003 V70 - Help with REM blowing fuse

brian2468 · Post by **brian2468** » 16 Jul 2012, 07:07

Hi all...

Have an 03 V70 2.4 Base model - Man. Trans.

Lost fuel gauge, rear door locks, etc. Found blown 10a fuse #1 in the REM. Replaced fuse - everything worked again. Short time later fuse blown again. Fuse 1 seems to be the power supply for the entire REM, and on some models also powers "cargo area lighting." From the wiring diagram, doesn't seem that my car has that lighting, so something in the REM is causing this fuse to blow.

I suspect a bad relay or shunt in the REM is causing this. Before I start pulling relays 1 at a time and replacing fuses, anyone have any experience with this issue? Haven't had any luck searching for this specific problem. Also, anyone have any tips on testing the relays with a meter?

Thanks!!!

Brian

Post by **fazool** » 16 Jul 2012, 08:04

Not intimately familiar with your model but I have worked on my own REM's (01 and 07 S60) and read a little bit.

Obviously something is shorting out, causing the main fuse to pop. In such cases, I usually suspect an actual short circuit such as an exposed wire or broken insulation.

I've read that on some wagob models the rear hatch door wire breaks from the flexing and shorts out. Might your short be related to something moving?

I would put a new fuse in then exercise everything while monitoring the fuse (wiggle all wires, move the door etc.

just an idea

brian2468 · Post by **brian2468** » 16 Jul 2012, 16:55

Hey Fazool.......

Spot on!!!!

Noticed that when I opened and closed the rear hatch, the center brake light flickered on and off. I opened up the wiring harness which runs along the left hand hinge. Several of the wires are completely disconnected/broken, and on the large red and black wires, the outer jacket has separated. I assume that when the red shorts to the black, it blows the fuse.

I am going to disconnect the battery and solder/shrink wrap the connections. Guessing that will solve the problem. Will post an update when its fixed. Also, I have a feeling that my inoperative rear wiper will also work when its reconnected.

Thanks!!!!

brian2468 · Post by **brian2468** » 16 Jul 2012, 20:14

Another update....

Fixed all the connections in the harness. Reconnected battery (with key in position 2 per numerous posts.) Everything works, including my rear wiper. No more blown fuses.

1 Problem - 3rd brake light stays on, even with car off. Problem is not a short in the harness - i pulled the connecter and have power at pin 3 which is the feed for the third brake light per the wiring diagram.

I am going to try leaving the battery disconnected overnight. Any other suggestions??

mikegarage · Post by **mikegarage** » 07 Nov 2012, 22:39

Hi Brian 2468,
Any luck in finding out why your 3rd brake light is always on? I have 2004 v70 with a broken liftgate harness as well. I fixed it like you100% correct and my 3rd brake light is staying on constant. I also checked at the connector and getting constant power on Yellow/red wire terminal 3. Wiring diagram indicates it is its own circuit from the REM not tied in with the regular brake light circuit. Leaving battery disconnected overnight and I will tackle this more tomorrow.

Post by **chrism** » 08 Nov 2012, 20:37

Here's what I found to be causing a multitude of electrical problems, including blowing fuse, in my 03 V70:

https://www.matthewsvolvosite.com/forums ... =9&t=47882

mbreed · Post by **mbreed** » 09 Nov 2012, 09:32

Service info from Vida:

The stop lamps are in the tail lamps. The lamps light when the stop lamp switch on the brake pedal is closed. The stop lamp switch is connected to the central electronic module (CEM). The signal from the stop lamp switch is sent on to the rear electronic module (REM) via a hardwired cable. The power supply for the lamps is via a directly connected relay on the rear electronic module (REM). In order for the stop lamps to work when the ignition is not on, there is no logic in the rear electronic module (REM) to activate the relay. The relay is activated directly by the signal from the stop lamp switch. The rear electronic module (REM) receives data via the controller area network (CAN) from the central electronic module (CEM) indicating that the stop lamp switch is activated.

In order to detect faults in the stop lamps, the rear electronic module (REM) detects the power consumption in the lamp circuit using a directly connected shunt. If the power consumption falls below a certain limit, a fault is indicated and a text message is displayed in the driver information module

There is a high-mounted stop (brake) lamp on the inside of the rear windshield. This lamp lights during braking together with the standard stop lamps. The stop lamp is activated when the stop lamp switch on the brake pedal is closed.

The high mounted stop lamp is supplied with power directly from the rear electronic module (REM). The lamp consists of a number of LEDs.

All I can suggest is checking the stop lamp switch. If the switch is not constantly on you can try pulling the REM fuse to reset it.