Hi, I have a 1986 E150 cargo van 4.9L 4 speed manual transmission. Can't get the back up lights to work. I replaced the switch. Checked the fuses with a volt meter. Checked the sockets for ground, showed good ground. Checked for voltage , no voltage coming to the sockets.Checked the plug that goes on the switch, shows no voltage coming to the plug. Any ideas?

 

Have you verified voltage coming to, and then from, the switch? That will tell you where to start looking.

In electronics, when troubleshooting, we do something called, "circuit splitting". We split up the circuit that has a problem into logical sections, or segments. For example, that switch is a logical split in the circuit. If you verify that voltage is getting to that switch like it should, you just tested the entire first segment, from the battery to the switch. It's all good, and now you start looking in the segment that is from the switch to the socket. On the other hand, if you have no voltage going to the switch, you need to look upstream from the switch. There might be a relay or a bad connection somewhere upstream.

It's a divide and conquer sort of thing. Pick a spot, test it, and then you know the problem is on one side or the other. Just to keep things fun, sometimes you have problems on BOTH sides!

It really helps if you have a circuit diagram that shows where connectors and switches are.

One more thing - make sure you verify voltage with a test light. Here's why: If there is a poor connection upstream of where you are testing, the voltage meter might show good voltage, but as soon as you get a load on it, it drops. It will 'power' the meter, but not a light bulb. This can trip you up if you aren't aware of it.

 

I did check for voltage at the plug. It didnt show any voltage. I checked the fuse with a voltmeter, both voltage and continuity. Looks okay. I also checked for ground at the sockets with a voltmeter, it looks okay too. Thanks for the tip on using a test light, good to know.