Reverse lights on in Park gear?

RUSTY396

MEMBER
2000 GMC SIERRA
5.3L
V8
2WD
AUTOMATIC
250,000 MILES

Reverse lights are on in park only and turn off in any other gear.
I have replaced the safety neutral switch; the rear lamp junction box checked the fuses and cleaned a few grounds I found that spliced off the harness onto the body.

Friday, January 20th, 2023 AT 1:41 PM

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

There is only one item that can cause this issue which is the park/neutral switch on the left side of the transmission. Is this what you replaced? Here are the reverse light wiring diagrams in the images below and how to correctly replace the switch as well. Please let me know.

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Friday, January 20th, 2023 AT 6:18 PM

RUSTY396

MEMBER
3 POSTS

Yes, that is the part I replaced, the park/neutral switch and the reverse light still stays on in Park.

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Friday, January 20th, 2023 AT 10:54 PM

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

There might be some wiring problems, as you can see from the wiring diagrams there is not much to the reverse light system. Can you remove the rear light housing to look for wiring problems? Also remove the bulbs to see if something has melted.

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Saturday, January 21st, 2023 AT 10:27 AM

RUSTY396

MEMBER
3 POSTS

Both bulbs are good, no melting around any sockets in either of the taillights.
I’ve pulled back some of the wire sheathing and the wires look good, no rubbing, pinched or exposed sections. How could I further check for wiring problems?

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Saturday, January 21st, 2023 AT 12:44 PM

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

Does the vehicle have trailer wiring? Also, please check out the reverse wiring diagram above because there is really nothing that can cause this problem except the park neutral switch.