I have a 1990 volvo 240 wagon and every time i try to turn the rear window defroster on it blows the fuse immediately. I recently replaced the tail gate harness, so i dont think that there are any broken wires in there. i took the dash off and looked to see if there were any loose wires behind the switch.Someone please help.thanks in advance.

the wiring harness through th etailgate hinge is probably worn out. Th e insulation on the wire, and the wire itself becomes brittle with time and eventually fails. The power supply wire is porbably shorted out to the hinge. Lift up the tailgate and inspect the wires, you should easily be able to see if they are broken. Search the archives, there are several descriptins on how to replace or repair the existing harness or install a revised harness that will have less ware and tear.

There is also a chance that the tailgate wiring harness has frayed. Alas I can't tell you which side the defroster wires are on, but checking and replacing them is not all that difficult. However, since you have to pull the rear corners of the headliner off, it does help to have the car in a warm place like a heated garage - I don't have a garage and I wouldn't want to play with the headliner in our 25 degree weather today here in CT!

The tailgate harnesses run from the 'ceiling' of the car up thru the 'gate hinges and into the gate. There is a multi-pin molded connector for each side, near the back corners not all that far from the hinges. As a diagnostic effort you could disconnect the connector, then check each side of the connector with a meter for power, ground, etc.

If you do find a bad harness, I recommend replacing both sides at the same time. You will need a helper to assist you with the tailgate removal and reinstallation - it's not heavy, just unwieldy. It took my 14-yr old son and me about 2.5 hours to do the job.

Check all the other things the circuit supplies. If you don't have the diagram, pull the fuse and see what else doesn't work, then put a good fuse in, don't try the defroster, just try everything else on the circuit, one at a time, until the fuse blows, when you blow the fuse look at what blew it (short..whatever) i.e. the fuse blew when you used the turn signal, so then you look at the turn sig stalk or more likely the turn lamps and assoc., wiring. Good Luck,
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patrick of montreal, '66/120, '83/245.

How's your overdrive?? I have an 88 240 DL sedan and the same fuse was protecting the rear defrost and the overdrive. The overdrive wiring was bad and the fuse blew, rendering the rear defrost inoperable.

Check your ground. Somewhere there is a bare/broken wire. You could run a temporary wire from the switch to the wiring for the defrost in order to test this theory. Patience wins out in these situations. Check your switch, trace the wire and you'll find the problem. Good Luck.