1990 Toyota Pickup with Automatic transmission. Backup lights don't work. I changed bulbs. But when in reverse, there is no power to sockets or in wires under the back of truck. I can't find if there is a fuse for backup lights. The neutral safety switch for automatic is very expensive. Is there a way to check to see if it is is good or not? Any other ideas?

 

Welcome to YotaTech.

Yeah, looking for electrical problems by replacing parts willy-nilly can get old really quickly. Here's the manual on the switch for an A340-H. http://web.archive.org/web/201408160...37parkneut.pdf It will probably match whatever transmission you have, but you can find out exactly by looking at your door pillar.

 

The Neutral Safety Switch soen't control the Backup Lights; there is a separate switch for that and they aren't expensive or difficult to replace:

https://www.rockauto.com/en/catalog/...mp+switch,4240

The switch is usually on the driver's side of the trans, more towards the rear. Be sure to check for worn away insulation on the wire that could be causing a short. As far as I know, the Backup Lights do not have their own fuse, but work off of the STOP/TAIL fuse (15 AMP).

 

Which wires? Which color? Where do they go? Got pics? Pls see signature.
There should be 12V to the backup light switch on tranmission when IG is on. On our 22R-E's it takes power from engine fuse. I don't know about yours.

 

I appreciate the responses. Just clarifying that my 1990 2 wheel drive R22 pickup is automatic transmission (114K miles -bought in 2010 from 90 year who bought it new). Someone wrote that backup lights are not on neutral safety switch, but is that the case just for manual?
The color of the wires that go to the backup lights are red with black stripe around wire. I had bundle open at back of pickup because years ago I added trailer lights. Red, of course, was not a part of trailer lights. A couple days ago, I opened it up to check if there was power in the wire when in reverse. Other lights work fine. I'll try to get some pictures on. FYI, the neutral safety switch has wiring that goes all the way up toward starter and breaks off into 2 or 3 connectors. I haven't inspected all of them, but those I did looked good.
https://www.rockauto.com/en/catalog/...ge+sensor,4584
This neutral safety switch is similar to mine, but it doesn't have the wiring bundle. Local auto parts store quoted me about $300.
I'll work on your suggestions on Saturday and respond again. Thanks again for your help.

 

Do you have the backup-light relay? If present, it's probably under the driver's side kick panel.

Before I replaced anything (switches, relays, even bulbs) I'd work carefully with my multimeter to find where the problem is. A bad switch is way down my list of suspects.

 

The backup light switch is completely separate from the neutral safety switch, so don't waste your time chasing the neutral switch. Attached is a wiring diagram from the '94 4-runner - the backup light switch is on the left side. Yours is likely similar. Pretty simple circuit. The backup lights are fused off of the gauge fuse, which runs a bunch of other stuff, so that is likely not the problem. Start at the switch and work your way back toward the lights until you find where the voltage has gone missing.

 

clint.hahn has an automatic, so I think the reverse contacts are part of the PRNDL switch (connector A v. connector B in the diagram).

 

I think you're right. No wonder it costs $300.

Life sure is simpler with a manual...

 

Second that!

 

Clint,
You need to
1) Find EXACT schematic for your truck. Toyota's of our era are a Frankenstein clan; schematics vary from FRACTION-OF-A-year/model/trim/engine/transmission.
2) Let us SEE what you're working on, especially because we are away from your truck. We don't even know which schematic to look at in order to help you. By showing us what you see, we can intelligently-guess which schematic matches yours.

A picture paints a thousand words. Please see my posts.
Start by showing us ACTUAL picture of your neutral safety switch.
Clearly show what color wires go to it. Show EXACTLY which pin each wire goes on.

Based on my own truck and the schematic RJR shares above, and on schematic of 1990-1995 4Runner I have (below):
1) Black-Orange wire going to the switch should have 12V when IGN is on. That comes from the gage fuse in the 1994 truck, engine fuse on earlier gens.
2) The wire on other side of switch should be Red. There should be 12V there when IGN is on and trans is in reverse.
3) The Red wire should have zero (or close) to one side of back-up bulb.
4) That same red wire should have SOME resistance to ground if bulbs are in.
5) That same ref wire should have INFINITE (open circuit or no continuity) to ground when both bulbs are out.
PLEASE LET US KNOW WHAT ON YOUR TRUCK IS DIFFERENT.

 

Everyone, I found solution, which turned out to be easy. I checked all fuses (those under dash) on driver side with light meter to see if they had power both sides. I had previously just inspected them. The one called CIG 15A was blown. I never noticed as I didn't use it. I replaced and got my back-up lights as well as the gear position lights on dash. ( P R N etc. ). Thanks for your support.

 

CIG 15A = Cigarette Lighter
Hmmm, I wonder what model-year takes power for Back-up lights from the CIG circuit.

 

My '94 EWD shows the CIG fuse powering the gear posn lights in the Combination Meter (also the clock, and would you ever guess, the cigarette lighter). So that part makes sense.

But I don't see how that fuse would affect the backup lights.

Of course, fuses don't blow on a whim; something shorted somewhere. And that short could have (temporarily) taken out the backup lights. I fear that clint.hahn's problem will recur in one form or another.

 

YUP, one potential cause could be this:
https://www.yotatech.com/forums/f199...l#post52023759