Reverse lights on 85 1 ton that was converted to auto

[Deadbuell]

Hello everyone this is my first post here! Well let's get started. I picked up a 1985 Silverado c30 that's in pretty dang good shape with the 454. It has a few bugs I've been in the process of working out and the one I'm on now is not having reverse lights. The truck originally had a manual trans in it which I didn't find out untill recently when I noticed the clutch pedal tucked behind the carpet and so I felt the trans tunnel and can feel the hole for the shifter. My question is could the PO have left anything out in the swap that would make the reverse lights not work. They did replace the steering column with a column shift. I just ordered a new column because while tightening the tilt I noticed some cracked prices in the old column. I'm leaning towards the neutral/reverse safety but figured I would ask first.

 

[glockholiday]

Can't help with why they might not be working but I have to ask, you checked the bulbs right?

 

[Deadbuell]

Yes lol that was what I checked first.

 

[yevgenievich]

On manuals the light switch is on the transmission it self, while on auto it should be on the column. They might just left the wires disconnected and never go the new connector.

 

[CSFJ]

I thought there were some differences in the harness between the two. Seems as though I've read a thread about the issues getting the back ups to operate when going from auto to manual. Kinda got the impression it was a little more involved than extending some wires to plug and play. I could be mistaken tthough.

 

[Keith Seymore]

I'd just wire them up to a separate toggle switch.

That way you can flip them on to help hooking up a trailer in the dark, etc.

I used to do that as a standard practice.

K

 

[kickdeez]

Here you go:

http://www.gmsquarebody.com/forum/showthread.php?t=15582&highlight=reverse

 

[skysurfer]

I'd just wire them up to a separate toggle switch.

I've done that too. The toggle switch I mounted under the dash had a bright red light attached so I wouldn't forget to shut them off.

 

[kickdeez]

I've been there too, lol. Assuming the factory switch is on the column, it should be same amount of effort to wire it up as it would be to wire up a toggle switch...and you cant forget to turn them off if you use the column switch.

 

[chengny]

There should be two dark blue wires connected to the load side of the fuse labeled DIR B/U:

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One of them is the factory power supply to the B/U lamp switch (the other is for the blinkers). If you are able to locate the dark blue wire for the B/U switch that would be good because it would probably be long enough to reach the switch at the column base. But if not, it doesn't matter where you tap into a power supply - use any convenient ignition switched circuit. Run that lead to one of the terminals on the switch - doesn't matter which one.

The other terminal on the switch must be connected to the LT GRN lead that runs back to the B/U lamps. If you look around under the dash you might find it just laying there - it will most likely not be connected to anything and will have no terminal connector.

If you can't find the cut off end under the dash, no big deal. Just release the two screws that secure the fuse block to the main harness connector on the firewall. They are in the lower left and upper right corners (3/8" heads I think):

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When the screws are free, gently draw the fuse block away from the main harness connector and tilt it to the right. The LT GRN feed for the B/U lamps transits the FW connector in the very top outermost bay, so it will be easy to locate and trace.

Engine side of firewall harness connector:

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Coming out of the connector and into the cab behind the fuse block:

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Bonus: While the block is released, if you were unable to locate the DK BLU power supply before, now would be a good time to find it where it connects to the back of the fuse holder.

If the replacement column is of the correct year (1985) there will be no neutral safety switch on the column base. They were long gone by then - replaced by a mechanical lockout of the ignition switch unless the shifter was in P/N. So, you will see just two terminals -that connect to the B/U light switch:

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Disregard the text about ACC & START - it was for another post.

 

[Deadbuell]

Wow great information guys. The new column should be in tomorrow and it's from a 1984-87. I will let y'all know more tomorrow as to what I find