Another Backup Light Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BLACK AND BLUE 67-72 · 10-03-2003, 02:32 PM

Is there a relay for the backup lights? Because what my problem is, is that I have swapped the original column for a tilt and the switches were different so I had to hook up the backup lights to a toggle switch, so when I flip it they come on. But the problem is when I turn them on they will only stay on for a short amount of time before they shut off, and when they shut off they cause all of the dash lights to dim down, I can flip the switch off and the dash lights return to normal. Then if I turn the switch back on they will not come on only cause my dash to dim, If I wait quite a while and try to turn the switch back on the backup lights light up? Any suggestions?

red71cheyenne · 10-03-2003, 02:36 PM

Which truck is this in, and what type of tranny are we talking about?

BLACK AND BLUE 67-72 · 10-03-2003, 02:58 PM

1972 with 350 turbo

red71cheyenne · 10-03-2003, 03:06 PM

Sounds like your switch is grounding out dash. You should be able to adjust your back up switch on the column just like on the non-tilt column. May require moving the switch housing around a little though. Insert a 1/8 drill bit into the switch contact and loosen the screws until it actuates freely. You will want the tranny in reverse for this, or the shift lever anyway. Your switch is probably giving you a dead short to ground when coupled with your back up switch on the column. Good luck, Jeff.

BLACK AND BLUE 67-72 · 10-03-2003, 04:04 PM

Well, the switches are different and so are the mounting positions the tilt is from a van and the switch position was above the stock location so when I tried to put the column in it would smash the switch because it was located where the column was bolted to the dash, so I had to use the old switch and just leave it hanging and then add a toggle switch to activate the B/U lamps.

red71cheyenne · 10-03-2003, 04:44 PM

You can re-mount the switch to the column lower down. Just drill the holes in it carefully lower down, approximately the same location and mount and align the switch. Its really not that hard. Hooking up the toggle switch gave you a ground though. Thats why your lights are dimming

BLACK AND BLUE 67-72 · 10-03-2003, 05:43 PM

Then there is another thing with moving the switch, the newer one has a longer switch lever to reach down into the column the original's lever is too short to reach. And also the connections are not the same so I can't just hook up the old connections because the plugs are different. So now what do I do??

red71cheyenne · 10-03-2003, 06:00 PM

Can you mount the newer switch and make it work as designed? If so, then you can just splice the new connector into your existing harness. Its got 4 wires right? Purple are your starter in and out for the neutral safety switch, and Dark Green and Light Green are the power and light leads coming from the fuse box and out to the back-up lights. I can email you the schematic if you con't have it. Jeff.

BLACK AND BLUE 67-72 · 10-03-2003, 07:01 PM

Well it's been a while since I looked at it but I think my problem would be that I have not only to cut through the outer tube, But if I'm not mistaken that I would also have to cut into the inner shaft, and don't really know how to go about doing that (The Inner Shaft) I'm not worried about the outer tube just the inner shaft. Has anyone else done this before?

red71cheyenne · 10-03-2003, 07:10 PM

I have not done the remount thing. When I put my tilt in, it came with the switch already mounted. Can you look at your 4x4 and see how that one is in there? Otherwise, TTT.

BLACK AND BLUE 67-72 · 10-03-2003, 07:23 PM

4x4's is still the orginal column on which it still has the orginal switch, in which is still the other style shorter switch lever.

BLACK AND BLUE 67-72 · 10-04-2003, 09:50 AM

ttt

71GMC_3/4T · 10-04-2003, 10:36 AM

If your switch causes the lights to come on and dim in a few seconds, you might have a bad circuit somewhere in your backup lights. Maybe a bad socket or a wire shorted to ground.
You took the two wires that were originally hooked to the backup light switch on the column and put the switch between them, right?
If I were you, I'd get a voltmeter and start measuring the voltage at the fuse box (reference chassis ground w/ black lead). You might have a fuse that's going resistive, or a bad connection at the fuse block somewhere.
Good Luck!

BLACK AND BLUE 67-72 · 10-04-2003, 11:48 AM

The backup lights come on and then after a short amount of time they shut completely off, and then the dash lights dim down until I shut off the switch in which the dash brightens back up, but if I turn the toggle switch back on the B/U lamps stay off and the dash lights dim down. However if I wait for a few min. then turn the switch on the B/U lights work again, when they do work the dash is just fine, only when the B/U lights go off does the dash dim down, that is why I was asking if they had a relay or something. It acts like a relay gets hot and shuts them off but after letting set for a few min. then they come back on. This is what is confusing me.

71GMC_3/4T · 10-05-2003, 11:02 AM

I just checked the wiring diagram (for a '73, which should be the same). It shows that the backup lights get fed from Ignition-On-and-Start. This circuit also feeds the turn signals, which is the only other load on this fuse.
My guess is that you wired it wrong. In my previous post, I asked you how you had wired it. How did you wire it? Hmmm?
Here is a quick check to try: Turn your headlight knob almost fully CCW (just before the dome light comes on). Try your backup lights again. Also, try it with the headlight knob fully CW (no dash lights at all). Let me know what you find...

jorgensensc · 10-05-2003, 12:04 PM

A little away from the remounting issue, but the toggle switch might be overheating. I had one hooked up to electric fans on a different truck awhile back and it had the same problems. Turns out too many volts were going through and causing the toggle to 'shutdown temporarily' Hope this helps a little. BTW I fixed it with a relay.

BLACK AND BLUE 67-72 · 10-05-2003, 01:20 PM

As far as the wiring goes, everything is stock from the factory plug that plugs into the neutral safety/backup lights back to the lights themselves. The only thing that I did was unplug it from the switch added two wires with spade connectors hooked to a toggle switch, and plugged them into the connector. I had thought about the switch overheating and felt it but it was cool to the touch, I don't know if it would get hot enough to feel or not. I do not think that the problem is in the wiring, but I am unsure about the switch.

71GMC_3/4T · 10-05-2003, 06:13 PM

Long shot here:
Your bed is not grounded well? When the backup lights are on, they are feeding back through the park lights and causing problems with your dash lights.

Does it flake out when the backup lamps are not installed? If this happens, you have a short somewhere in your backup light wiring. If not, check the grounds!

To check the ground: Get a long piece of AWG 14 wire, about 20 or so feet. Clamp one end to the battery (-) terminal. With the backup lights on, and the park lights on also (so you can see the dash lights), touch the metal shell of the lamp housing (with lens removed). The backup lamps should come on and stay on.

Oh, crap! You *do* have your tail light housings installed, right?? If they aren't grounded, or not well, you will have the problems you are describing!

This can't be that tough...

Oh, yeah, what kind of switch are you using? Try shorting across the contacts with a screwdriver (old one!) when it is supposed to be on and see if the lights start to work. However, a bad switch shouldn't be causing your dash lights to go out, unless it's shorting to the chassis somehow.

Good Luck!

10-03-2003, 02:32 PM	#1
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Another Backup Light Question Is there a relay for the backup lights? Because what my problem is, is that I have swapped the original column for a tilt and the switches were different so I had to hook up the backup lights to a toggle switch, so when I flip it they come on. But the problem is when I turn them on they will only stay on for a short amount of time before they shut off, and when they shut off they cause all of the dash lights to dim down, I can flip the switch off and the dash lights return to normal. Then if I turn the switch back on they will not come on only cause my dash to dim, If I wait quite a while and try to turn the switch back on the backup lights light up? Any suggestions? __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-03-2003, 02:36 PM	#2
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	Which truck is this in, and what type of tranny are we talking about? __________________ 1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty

10-03-2003, 02:58 PM	#3
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	1972 with 350 turbo __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-03-2003, 03:06 PM	#4
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	Sounds like your switch is grounding out dash. You should be able to adjust your back up switch on the column just like on the non-tilt column. May require moving the switch housing around a little though. Insert a 1/8 drill bit into the switch contact and loosen the screws until it actuates freely. You will want the tranny in reverse for this, or the shift lever anyway. Your switch is probably giving you a dead short to ground when coupled with your back up switch on the column. Good luck, Jeff. __________________ 1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty

10-03-2003, 04:04 PM	#5
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Well, the switches are different and so are the mounting positions the tilt is from a van and the switch position was above the stock location so when I tried to put the column in it would smash the switch because it was located where the column was bolted to the dash, so I had to use the old switch and just leave it hanging and then add a toggle switch to activate the B/U lamps. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-03-2003, 04:44 PM	#6
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	You can re-mount the switch to the column lower down. Just drill the holes in it carefully lower down, approximately the same location and mount and align the switch. Its really not that hard. Hooking up the toggle switch gave you a ground though. Thats why your lights are dimming __________________ 1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty

10-03-2003, 05:43 PM	#7
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Then there is another thing with moving the switch, the newer one has a longer switch lever to reach down into the column the original's lever is too short to reach. And also the connections are not the same so I can't just hook up the old connections because the plugs are different. So now what do I do?? __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-03-2003, 06:00 PM	#8
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	Can you mount the newer switch and make it work as designed? If so, then you can just splice the new connector into your existing harness. Its got 4 wires right? Purple are your starter in and out for the neutral safety switch, and Dark Green and Light Green are the power and light leads coming from the fuse box and out to the back-up lights. I can email you the schematic if you con't have it. Jeff.

10-03-2003, 07:01 PM	#9
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Well it's been a while since I looked at it but I think my problem would be that I have not only to cut through the outer tube, But if I'm not mistaken that I would also have to cut into the inner shaft, and don't really know how to go about doing that (The Inner Shaft) I'm not worried about the outer tube just the inner shaft. Has anyone else done this before? __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-03-2003, 07:10 PM	#10
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	I have not done the remount thing. When I put my tilt in, it came with the switch already mounted. Can you look at your 4x4 and see how that one is in there? Otherwise, TTT.

10-03-2003, 07:23 PM	#11
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	4x4's is still the orginal column on which it still has the orginal switch, in which is still the other style shorter switch lever. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-04-2003, 09:50 AM	#12
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	ttt __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-04-2003, 10:36 AM	#13
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	If your switch causes the lights to come on and dim in a few seconds, you might have a bad circuit somewhere in your backup lights. Maybe a bad socket or a wire shorted to ground. You took the two wires that were originally hooked to the backup light switch on the column and put the switch between them, right? If I were you, I'd get a voltmeter and start measuring the voltage at the fuse box (reference chassis ground w/ black lead). You might have a fuse that's going resistive, or a bad connection at the fuse block somewhere. Good Luck! __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

10-04-2003, 11:48 AM	#14
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	The backup lights come on and then after a short amount of time they shut completely off, and then the dash lights dim down until I shut off the switch in which the dash brightens back up, but if I turn the toggle switch back on the B/U lamps stay off and the dash lights dim down. However if I wait for a few min. then turn the switch on the B/U lights work again, when they do work the dash is just fine, only when the B/U lights go off does the dash dim down, that is why I was asking if they had a relay or something. It acts like a relay gets hot and shuts them off but after letting set for a few min. then they come back on. This is what is confusing me. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-05-2003, 11:02 AM	#15
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	I just checked the wiring diagram (for a '73, which should be the same). It shows that the backup lights get fed from Ignition-On-and-Start. This circuit also feeds the turn signals, which is the only other load on this fuse. My guess is that you wired it wrong. In my previous post, I asked you how you had wired it. How did you wire it? Hmmm? Here is a quick check to try: Turn your headlight knob almost fully CCW (just before the dome light comes on). Try your backup lights again. Also, try it with the headlight knob fully CW (no dash lights at all). Let me know what you find... __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO



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10-05-2003, 12:04 PM	#16
jorgensensc Registered User Join Date: Jul 2003 Location: Cypress, Tx Posts: 4,005	A little away from the remounting issue, but the toggle switch might be overheating. I had one hooked up to electric fans on a different truck awhile back and it had the same problems. Turns out too many volts were going through and causing the toggle to 'shutdown temporarily' Hope this helps a little. BTW I fixed it with a relay. __________________ 1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE

10-05-2003, 01:20 PM	#17
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	As far as the wiring goes, everything is stock from the factory plug that plugs into the neutral safety/backup lights back to the lights themselves. The only thing that I did was unplug it from the switch added two wires with spade connectors hooked to a toggle switch, and plugged them into the connector. I had thought about the switch overheating and felt it but it was cool to the touch, I don't know if it would get hot enough to feel or not. I do not think that the problem is in the wiring, but I am unsure about the switch. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-05-2003, 06:13 PM	#18
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	Long shot here: Your bed is not grounded well? When the backup lights are on, they are feeding back through the park lights and causing problems with your dash lights. Does it flake out when the backup lamps are not installed? If this happens, you have a short somewhere in your backup light wiring. If not, check the grounds! To check the ground: Get a long piece of AWG 14 wire, about 20 or so feet. Clamp one end to the battery (-) terminal. With the backup lights on, and the park lights on also (so you can see the dash lights), touch the metal shell of the lamp housing (with lens removed). The backup lamps should come on and stay on. Oh, crap! You do have your tail light housings installed, right?? If they aren't grounded, or not well, you will have the problems you are describing! This can't be that tough... Oh, yeah, what kind of switch are you using? Try shorting across the contacts with a screwdriver (old one!) when it is supposed to be on and see if the lights start to work. However, a bad switch shouldn't be causing your dash lights to go out, unless it's shorting to the chassis somehow. Good Luck! __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

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