88' Ford Ranger xlt supercab
2.3l, 5sp, 4x2

Tail light problem: My driver's side tail light turns on, but will not blink or come on during breaking. I have tried to put a new bulb in, but it does the same thing. All other lights flash, and the other tail light comes on when I hit the brakes, only the left rear will not.

I did some searching, thinking maybe it could be a fuse or the flasher, but I don't think it would just screw-up one light. Would it?

Suggestions?

 

If you have a multimeter, check for 12 volts to ground at the socket when its supposed to be blinking, if that's ok, check for an open socket ground connection. If the socket ground connection is bad, use a jumper lead & probe to the lamp shell & see if it'll light up & blink, if it will, you know its ground is faulty.
If no B+ to the socket, begin tracing the wiring back to ward the cab, looking for pinch point, rub spots & faulty electrical connectors. Did the problem come about after some event????

 

Theres separate circuits in the multifunction switch for turn sigs & hazards. Do the hazards work

 

87 XLT - you know, I kind of dismissed the switch in the column as I have replaced it before (prob 2x), but that plug has always looked bad like it melts in some areas..

Yes, all the hazards work, except for that driver's rear.

Pawpaw - I do stink with a multimeter. I have been known to test wires in my house that were "multi-phase" (or something like that), and not find voltage, only to find it really is live when I cut through it.

I will assume no, there is no voltage since a working bulb does not light in that socket.

I have lost my head lights before due to the plastic melting over the contact in that switch, so it sounds like I am taking the column apart again.

 

If the left rear hazard did work the MFS would definetely be the problem and it still could be.

Heres how to test the MFS on an 87, your 88 is probably the same.

Remove the connector & hook up your ohm meter to terminals 44 & 9 and move the lever to left turn. Should see a dead short.

For comparison connect to 44 & 5 and turn signal lever to right turn. Should see a dead short.

Since the left rear comes on with the headlights the ground is ok.

 

I will have to try that. Yes the "low light" comes on, but the bright "high light" does not, for any switch. My concern will be how I identify the plug wires. I don't remember seeing numbers on it and I know one area of it has had pieces of the melted plastic broke away so the connector will work again.

Seems like "too much voltage" is getting to the headlight contacts causing it to melt. Is that possible? And how?

 

I'm not sure if those terminals are marked or not. Wish I could post pics. My factory diagrams include a picture of the switch & which terminals are which.

Some guys have added a headlamp relay to prevent burning the contacts.