Hi! I'm new here but been reading the forum for some says -- so let me start by thanking everyone for your posts. I apologize for my English as I'm not a native speaker.
My 2007 V70 started showing "rear hatch open" messages and blowing rear wiper fuses. I found a worn tailgate wiring harness at the hinge, as described in several topics. Many of the wires were completely cut and the remainder worn bare. After thoroughly exposing each, cutting, soldering and re-isolating, and moving the harness a bit upwards I'm quite certain that the harness is fine now. I was fortunate to have no problems finding the correct pairs to be soldered. Rear wiper and rear hatch detection are now fine. One issue remains, though: The rear license plate bulbs do not illuminate.
The bulbs are ok, but the voltage is too low at 9.2V. I revisited the harness to find the soldered wires and isolation fine. Neither is there any resistance from REM connector to bulb connectors (10/3). Voltage from the REM pins (F:5 and F:10) is also similarly low, 9.2V, which excludes the wiring harness, I guess.
Any thoughts how to continue troubleshooting? Is there any serviceable parts in REM?
2007 V70 License plate light low voltage
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packetfire
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TL;DR - Check your grounds!
You have measured a low voltage for the license plate bulbs, but you said nothing about the other running lights ("position lights" in Volvo-speak) in the rear end that also run off the REM. I'll assume that the taillights work fine, which is a big clue that this problem is unique to the license plate bulbs, and not a general issue with the REM.
I would suggest measuring the voltage between the power wire to the license plate bulbs and the shared ground point between the taillight assembly and the license plate bulbs. On my 2001 v70, it looks like the driver's side taillight assembly shares the ground with the license plate bulbs.
While it is possible that the relay could be to blame, this would be a strange way for a relay to fail.
You have measured a low voltage for the license plate bulbs, but you said nothing about the other running lights ("position lights" in Volvo-speak) in the rear end that also run off the REM. I'll assume that the taillights work fine, which is a big clue that this problem is unique to the license plate bulbs, and not a general issue with the REM.
I would suggest measuring the voltage between the power wire to the license plate bulbs and the shared ground point between the taillight assembly and the license plate bulbs. On my 2001 v70, it looks like the driver's side taillight assembly shares the ground with the license plate bulbs.
While it is possible that the relay could be to blame, this would be a strange way for a relay to fail.
1982 240DL: Drove it 32 years and 1.5 million miles (sold, even still had mint leather!)
2001 v70 2.4T: The most expensive $1500 car I ever bought ("Volvo Turbo" - what an oxymoron!) (sold)
2004 v70: Far less fatally-flawed v70 - It served well (sold)
2010 v50: Smaller, slightly sportier wagon. Its got a spoiler, so I upgraded with sway bars!
2001 v70 2.4T: The most expensive $1500 car I ever bought ("Volvo Turbo" - what an oxymoron!) (sold)
2004 v70: Far less fatally-flawed v70 - It served well (sold)
2010 v50: Smaller, slightly sportier wagon. Its got a spoiler, so I upgraded with sway bars!
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jimmy57
- Posts: 6694
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If you have low voltage out of REM you may have to reset REM. 2005 and later are tranistor power circuits and when some faults occur the REM can store codes and put the circuit in safety mode or off.
Turn Key off, all doors closed but tailgate open with latch manually closed and then wait 5 minutes. Disconnect battery (-) cable and touch it (+) post for 10 seconds to drain capacitors to assure no residual power that would keep the modules from going fully off. Now connect the (-) cable and lock and unlock doors using remote. Check to see if license lamps now work.
VIDA can clear the codes which resets the REM but you may not have that and the mentioned way will work if that is what is wrong.
Turn Key off, all doors closed but tailgate open with latch manually closed and then wait 5 minutes. Disconnect battery (-) cable and touch it (+) post for 10 seconds to drain capacitors to assure no residual power that would keep the modules from going fully off. Now connect the (-) cable and lock and unlock doors using remote. Check to see if license lamps now work.
VIDA can clear the codes which resets the REM but you may not have that and the mentioned way will work if that is what is wrong.
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