Ok so my reverse lights aren't working. The brake lights are working, my parking lights are working but my tail lights won't work. I've replaced the circuit board, the light bulbs and checked the grounds, the harness and the fuses. Nothing seems wrong, but its obvious that something is wrong. Is there something I'm missing? Its for a 1998 Chevrolet silverado k1500 4wd 5.7 vortec

 

What do you mean by “checked the grounds, harness and fuses”? What did you do to check them? Did you do a visual check, did you check for power using a test light or meter? Please clarify.

Do you have any trailer wiring spliced into the harness? Was it done using scotch locks or butt connectors that aren’t sealed? (Note: Electrical tape doesn’t count as a seal.)

Even if the external looming of the harness looks good, the wiring itself can still be damaged.

If the brake lights and parking lights (what about the license plate lamps and turn signals?) are working, then power for the reverse and tail lights needs to be checked at the 4 way connector for the lamps using a meter. You need to know how much power is getting to the circuit board.

For the tail lights - Check for battery voltage with the headlight switch on - power should be on the brown wire. I don’t think the key needs to be on but if you don’t get anything with the key off, see what you get with it on. Left turn signal can be checked on the yellow wire and right turn signal can be checked on the dark green wire.

For the reverse lights, chock the wheels and/or set the parking brake. Turn the key on, engine off, and shift to reverse - power should be on the light green wire.

Anything less than 11.5 volts on either is reason to suspect the harness, with the exception being if the battery is less than 11.5 volts. Sometimes it doesn’t take long to drag down the battery depending on its state of charge, so turning off all accessories or hooking up a charger while you test the circuits is recommended.

 

i am an commercial electrician so yes i do know how to check the grounds and see if fuses are blown and i did a visual check on the harness meaning i took the wire loom off and checked all the way through and no cuts or any nicks in the wire. I'm thinking it is the neutral safety switch. And yes there is a trailer wire spliced in with heat shrink butt connectors.

 

Awesome. I’m an auto mechanic. Perhaps we can learn from one another!

You need to read voltage at the tail light connector with a meter. Period. Until then you don’t know what’s going on.

Maybe these will help.

 

when it says (left side of transmission) backup lamp switch is that a part of the neutral safety switch? In (fig 1)

 

yes it is

 

It is if your truck is automatic. If it’s a manual, the backup lamp switch is on the transmission and the neutral safety switch is mounted under the dash and open/closed by the clutch pedal.

 

thank you gumby22 i so so appreciate it and everyone else who put in some input. It was the neutral safety switch/reverse lamp switch. And once again thank you guys

 

You’re welcome.

In your original post you said your tail lights weren’t working either. Did you get that figured out?

 

i reread my post and i ment only my reverse lights