Need help with wiring issue

[ScottH]

Just picked up a 87 V10 and trying to figure out why the blower motor wont work. I did some testing & the motor is good, relay was just replaced, resistor looks good. The problem is I am not getting power to any of the above. Pulled the dash switch and swapped with another used one I had, same thing, nothing. Tested for power on all four leads of the switch plug & nothing. Changed out both the Heater & AC fuses, still nothing.

Can anyone tell me where the power to the switch comes from? In the wiring diagrams it appears to be from a BRN wire which originates from the fuse box. Also one diagram indicated there was an inline fuse on this wire.

If anyone has any suggestions or could shed some light on this I would appreciate the help. BTW not sure if it makes a difference but it equipped with AC.

Thanks
Scott

[chengny]

One thing that might be throwing you off - the hot wire for the A/C system doesn't tie in at the blower switch. It runs from the fuse block, past the back of the control panel, doubles back at a Y in the harness and then terminates and feeds the entire system at the selector switch plug.

Speaking schematically - within the selector switch assembly, that brown hot lead splits into two brown/white wires.

After that point, the BRN/WHT wires become the hot leads. One runs over to the blower speed switch and the other feeds the common terminal of the resistor stack.

Find the brown wire at the selector switch. It will initially head over to the right within the harness. But then, at a harness Y split about one foot away, it makes a 180 degree turn. From there it heads off to the fuse block.

In the list of things you have changed/checked I don't see the selector switch mentioned. If you have a spare switch maybe try replacing it. If the that switch is bad you will not get power at the blower speed switch.

[ScottH]

thanks very much, really appreciate the info. btw am I correct in assuming the "selector switch" is the main ac/heat control panel that the blower switch attaches to?

Also from ur description is sounds like I should have power to the brown wire that goes to the resistor (regardless of selector switch power), is that correct? I ask because there is no power to the resistor as well.

[ScottH]

good news....swapped out the selector switch with another one I had & it works.

thanks very much for ur help.

Scott