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Radio goes off when putting it into Reverse

70sixpkrt

70sixpkrt

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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?
 
70sixpkrt said:
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?
Click to expand...

Simple, just don't back up....

Doubt it has anything to do with the reverse light switch, maybe the dash reverse light is using the same ground & it's a little corroded, Sometimes an extra load causes the circuit to fail, take that load awhile & the circuit goes back to working... Also might be corrosion at the fuse box....
 
Shitty radio station....:D
I'm thinking also safety feature..... might be just to unplug at the tranny, put it in reverse, put it back in park, plug it back into tranny, start it up and put into reverse. We did this at a car show this summer for 68 Charger and it seemed to work. Not sure if its even the right thing to do but it worked.
 
The reverse switch is a simple switch...nothing more.

You have wiring issues. Nothing to do with reverse gear.
 
By the manual, the back up light switch is connected to the radio harness. 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.
 
Last edited:
do not use 85-90 differential gear oil in your trans unless it is specifically specified for manual transmissions
sulfur in gear oil eats brass synchros
use trans oil
the oem oil is not even made anymore
but there are newer synthetic 75x and 80 x ones that work well
 
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.
 
I thought that you were going to put the old gear oil back in to see if that fixed it ? :poke:
 
wyrmrider said:
do not use 85-90 differential gear oil in your trans unless it is specifically specified for manual transmissions
sulfur in gear oil eats brass synchros
use trans oil
the oem oil is not even made anymore
but there are newer synthetic 75x and 80 x ones that work well
Click to expand...
I am using GL4 which is synchro friendly.
 
I thought that you had a better sense of humor.
 
You may still have an issue? If the switch was grounding out (dead short) it should have blown the fuse. I think the radio fuse is only like 5-Amps?
So either the switch had a soft short where it was higher resistance between the case and switch and not a dead short, or you have some resistance in the feed circuit like a bad crimp connection or something that creats resistance under current load and is limiting current to where the fuse does not blow.
 
holy punctuation Batman
dangolecaintunderstanjibberishdangitmanolerunonsintentncedangman
 
wyrmrider said:
do not use 85-90 differential gear oil in your trans unless it is specifically specified for manual transmissions
sulfur in gear oil eats brass synchros
use trans oil
the oem oil is not even made anymore
but there are newer synthetic 75x and 80 x ones that work well
Click to expand...
I did not know that.
I tried to use synthetic back in 2004. I modded the cones, and I modded the brass, and I had that trans out three times in a week trying every trick I knew. In the end I put the EP oil back in there with 50% ATF, and Shazzam that trans shifts nice. I'll have to go see if I got some EP oil left and what I mighta put in there.
Good to know.
I had taken it down twice more before that and slickshifted firstly second gear, and then third, wow what a difference.
 
451Mopar said:
You may still have an issue? If the switch was grounding out (dead short) it should have blown the fuse. I think the radio fuse is only like 5-Amps?
So either the switch had a soft short where it was higher resistance between the case and switch and not a dead short, or you have some resistance in the feed circuit like a bad crimp connection or something that creats resistance under current load and is limiting current to where the fuse does not blow.
Click to expand...

Just changed the back up switch and the radio stayed on when putting it in reverse.
Don't know how to post a video clip.
 
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