Radio goes off when putting it into Reverse

[70sixpkrt]

I changed my transmission gear oil today and noticed that when I put it into Reverse my radio goes off and then on. It did blow the fuse once. It's a 4 speed. I was using Passon Perf gear oil and switched to 85W90 gear oil. I did add the trunk light harness that is behind the drivers side kick panel last month. I don't remember if it did this before adding the trunk light harness. The stereo is an aftermarket one which I put in about 20 years ago. Could it be a bad reverse switch at the tranny?

[krops cars]

All the switch does is send power in and back out. You could unhook the wires take an ohm meter. Put one lead on the side of the switch and put the other lead on the wire terminal on the switch. If you have continuity its junk. If not problem is else where.

[70sixpkrt]

By the manual, the back up light switch is connected to the radio harness. So I unplugged the plug to the reverse switch on the tranny. Car on accessory put it into reverse the radio stays on. No reverse light on the dash since it is unplugged. Hooked up a jumper wire from one female to the other female lead on the plug. Car on accessory the reverse light on the dash is on. Put it into reverse and the radio stayed on. To me it sounds like a bad back up light switch.

[krops cars]

I agree.

[Ghoste]

Car could be possessed. 

[TexasStroker]

Car could be possessed. 

Maybe a previous owner backed into a pole, so the car takes it upon itself to garner full attention, lol.

That said, I would try replacing the switch as well.

[70sixpkrt]

I unplugged the plug and hooked up a test light. I put it in reverse. Grounded the test light and then touched the each terminal on the switch. No light from either side. Did the same with the plug. Light came on and radio stayed on. Bad back up switch?

[70sixpkrt]

So I got a new back up switch yesterday. Plugged the plug to the new switch and pressed the ball bearing. The reverse light went on and the radio stayed on. I touched the switch to the trans for a ground and pressed the ball bearing. Reverse light went on and the radio stayed on. Looks like it was the switch.

[TexasStroker]

Glad you got it fixed!