Fuse 23 (AWD) blown 2007 XC70

Post by **erikv11** » 10 May 2023, 14:27

About 200 miles in to a 600 mile drive the car hiccuped and then the anti-skid message came up and the triangle illuminated on the dash. After the trip when I started troubleshooting I discovered fuse 23 in the cargo compartment (7.5 A, for the DEM) was blown. Replaced it and the warnings went away; the car has been fine for a week but I wonder if I should be bracing or preventing for some other issue.

I replaced Haldex pump, filter and oil in Dec 2020, that was 30k miles ago. Installed new Volvo branded pump and fluid. Inspected the connectors at the DEM this week and they are tight and clean inside.

What may cause this fuse to blow randomly? Anything I should check or watch for?

Post by **Krons** » 10 May 2023, 15:42

If no codes I’d simply watch closely. Only thing I might suspect is voltage spike. Any funny alternator type stuff happening?

My kids 05 XC90 recently had a high voltage warning on the dash, shut it down and never came back since. Alternator in it is a recent aftermarket unit from previous owner, I threw in a voltage regulator on my last FCPEuro order to swap in when I get a chance.

Post by **scot850** » 10 May 2023, 16:28

Just looked at FCP Euro price for a voltage regulator. How can a Bosch part be $38 and a Volvo part $365?

1000% mark up on a part??! Sheesh!!

Neil.

XC70Rider · Post by **XC70Rider** » 11 May 2023, 11:18

That 7.5A blew on me last month. It was the trailer wiring harness shorting the chassis. I haven't used the trailer hitch since I got a pickup 3 years ago so I removed the harness.

Post by **erikv11** » 11 May 2023, 17:14

No codes since the reset. I'll have to watch for other alternator-like symptoms.

Also interesting about the trailer wiring thanks - I do have trailer wiring back there. Did you locate the short or something? I'll inspect it.

XC70Rider · Post by **XC70Rider** » 12 May 2023, 12:04

I assumed it was the trailer hitch harness that caused the short cause I just hooked the positive lead of the harness onto the new battery I inserted in the trunk. I didn't recall what terminal it was for since I haven't touched the trailer hitch in 3 years. The harness is right below the REM which the DEM communicates thru. I've had no errors since removing the trailer hitch harness and replacing the DEM 7.5A fuse.