workin on a 1990 240DLover drive relay gets smoked. customer replacedworked for 10 min than quit again. obvously there is somthing shorting out the relay, and the cost of these things i cant just keep testing. i bypass it and apply the selonoid to test that. my only guess is that the selonoid gets hot and shorts out. in turn shorting the relay? any ideas?



Already Tried:
tested the odSELONOID with a 12v power suply. it operates fine.the owner clames to have replaced the od switch, witch seems to be in working order. the customer has also replaced the relay, vehicle worked for about 10 min then lost over drive again. when tested with a meter the output of the relay is 12v, but if i put a load inline(an automotive light bulb) the bulb bairley lights, and i only get 1 volt, with proves the relay fails under a load, but i cant test the system with out a new relay, and these things are going for 50 bucks, kinda steep if all i do is blow them trying to fix his problem.

 

My guess is that a lead that is supposed to be 12 V is shorting to ground. You'll have to dive into the wiring diagram to figure out which lead that is and then probe the socket for that wire where the relay plugs into. If you don't get 12 V or so on a supposedly hot lead, then test voltage between that socket and ground. If you get 0 volts or some small number, thenthat wire is shorting out. Trace back along that wire to find the short.

I would guess that the hot lead is supposed to be (1) always hot or (2) hot at ignition "On," not "Start." I could be wrong on this.

These wiring diagrams are not easy to follow. Good luck!

 

Buy the OD bypass plate (makes it always active) from IPD and be done with on of Volvo's biggest headaches.