86 SDL, no power to power seats
 

Where do I start? I get nothing on either seat with key on, running, door open and in or out of seat.

I have (part of) an "Electrical Troubleshooting manual " that covers 1986 through 1991. Its missing a bunch of pages in the first part but has diagrams that seem to cover my problem.

I'm confused (no kidding) that the manual shows a relay "H" in the fuse box, but in that location in my fuse box there are two red fuses. However, FYI this is one of the early models that did not have the external fuse 16 update. (but soon will)

I see fuses a, b, 15 and 17 along with a diode and the mystery relay are involved. I have replaced the fuses with no change.

Help if you can and please treat with kid gloves. You are dealing with an electrical ignoramus.

Thanks
Harry

Go into the fuse box and find the power seat relay.

Facing the box from the left side of the vehicle, the fuses are on your left and the relays are on your right.

You'll see four relays in the first row (closest to you).

You'll see three relays in the second row.

Pull the first relay in the second row (closest to the fuses).

Turn the ignition to position 2.

Check for voltage at socket #4.

Report back with results.

Brian, I don't have that relay.

Two things that may not be related, one, I just bought this car back from the guy I sold it to about two years ago. He spent a ton of money on it, but I don't know much of what was done in this area. Two, my manual states that fuse #16 was eliminated as of end number 269896 and my number is 267785. I know this is for the blower motor fuse, but it may indicate I have a different fuse box.

I hope my picture shows.

Thanks
Harry

See the two red fuses that are in the stated location? The FSM shows these fuses sitting above the relay. See if you can remove the fuses and the relay.

The relay that you don't have is to the right of the power seat relay. It's for the air pump clutch on a gasser.

No voltage on pin #4. Middle socket, close to fender. Pins and sockets look clean.

I was not sure what key position is #2, so I tried it in all positions with same results. I verified meter before each test to make sure of a proper ground.

Thanks
Harry

Now, please make the same test with the left front door open and the keyswitch off. If you still get no voltage, repeat the test with the right front door open. If you still get no voltage replace fuse #2, clean the contacts, and make the tests again.

Verify that there is 12V at fuse #2.

No voltage on pin #4 before or after the new #2 fuse cleaned with Diox. 12 volts on each side of #2.

Thanks
Harry

Did you try it with the doors open.........first the driver........then the passenger?

Yes, I should have said that, sorry. I did just as you said and again veified the meter with each read.

Last test:

Verify that you have voltage at fuse #17 and the contacts are clean.

No voltage at #17, both connectors with fuse out, fuse tested good

Turn the key to the #2 position (run) and retest.

I rechecked #17 with the switch in "run" position and had 12 volts through the fuse.

Brian, I think I was doing this at the same time you were telling me to do it.

Go in the fusebox and find the power seat diode.

It's in the third row, directly behind the relay that you just pulled out. It's the smallest thing in the box....about 1/4" wide and 1" long.

Pull this diode out and, hopefully, there will be two contact points beneath it. Take a test wire and jump the contact points.

Turn the key to the run position and verify that the seats now work.