Alright, I have a 1991 740. Changed out the factory stereo and now when I switch my headlights on, they do not work. The brights work...and just the running lights work, but when I move the switch all the way to the headlights, they all go out. I touched nothing but the radio wires. I am way confused!!![&:] Help anyone!

 

Only your dash lights are connected to the radio.They are connected for the dimmer systeman you remove the radio easy and unplug to see if the headlights work?You can check your fuses and make sure a fuse didnt blow.Make sure all extra wires are taped up good and not touching anything causing a short.Might just be a fluke that something went wrong after installing the radio.

 

Alright... I pulled my stereo back out and looked to see what of the original wiring was left unconnected. There is one light blue wire, one white wire and two yellow/white stripe wires. Do you know if any of these need to be connected in order for the headlights to function? Here are the exact symptoms. If I turn the headlight switch to the running lights, the running lights function and I can keep the brights on by holding the switch back. If I switch the headlights to the second position(lights on), the running lights switch off, the dash lights switch off and the headlights do not come on. HELP? Once again it's a 91 740 sedan. Are the yellow/white stripe wires illumination/dimmer wires? Since they are disconnected, should I have wired them together and them taped them off? They were originally connected in the same socket at the back of the factory stereo. I've put in probably 20 aftermarket stereos in my time and have never had an issue like this. Thanks to anyone who can help. Oh, also... I checked and cleaned every fuse.

 

YES!!!! OK, for anyone who is interested. If you install an aftermarket stereo that does not have a wire for the faceplate illumination and you do not use a wiring harness, you must reconnect the two yellow and white striped factory wires or your headlights will not work. I am assuming if you leave them separate, then you are not completing a circuit. I reconnected those 2 and the headlights came right on. Don't y'all just love Volvo's eccenticities? Thank you all for being a nice sounding board. I realize the wires are only for the dimmer switch, but they play a much bigger part.

 

Im glad it was only something that simple.I have seen this once before.