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Author Topic: 1991 Chevy c1500 electrical troubleshooting  (Read 16261 times)

pdangerp

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1991 Chevy c1500 electrical troubleshooting
« on: November 07, 2014, 08:29:04 PM »

I noticed The reverse lights were not working on my truck. I figured that since both of them were out, it must be a fuse or a switch.

I checked the fuse and figured out how to remove the neutral safety switch from the steering column and disassembled that. Both of them seemed to be working. I used my multimeter to check the continuity of both of those items and they rung out okay.

Then I decided to follow the voltage all the way back. I started at the fuse and had 12 volts, then checked the harness for the neutral safety switch (prndl321). Then I followed the wiring all the way back to the rear bumper checking connectors as I went along. I was able to identify 12 volts while the vehicle was in reverse all the way back to the trailer split connector.

Then I cleaned the ground point at the back of the frame. Then I removed both tail light housings and found 12 volts at each connector. Could both bulbs have gone bad on me at the same time? I did continuity checks on the housings themselves and found that the fault was between the positive and ground for only the reverse lights on both housings.

When I opened up the first housing, there were no burnt out bulbs. Upon closer inspection, whoever replaced the bulbs last time had swapped a two filament bulb with a one filament bulb inside the housing. I swapped them back to the way they should be and now it rings out okay with the continuity tester.

When I opened the second housing, I discovered the previous owner had only replaced the bulbs on one side and the original reverse bulb had burned out.

What are the odds of two completely different reasons for the lights not working? Pretty odd huh? I wish I had done the simple thing and looked at the bulbs first, but I didn't think it could be such a coincidence.

By the way, the original circuit board in the tail light has bulbs that are glued in or the connectors have melted over the last 20 years. I have a new one, but it uses different bulbs and I will need to pick them up tomorrow.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #1 on: November 07, 2014, 10:21:44 PM »

Also, I managed to kill the battery while performing testing with the engine off. Luckily I have a charger.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #2 on: November 08, 2014, 09:54:12 AM »

Bought the bulbs and put it back together. Works just like I thought it would.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #3 on: November 08, 2014, 10:15:46 AM »

I've found that there just isn't as much information on the Chevy trucks available as there is for the Jeep Wrangler. I had to do a lot more digging to find any good diagrams. Because of that, I wanted to post up some of the drawings that I have found, and maybe other people searching can be lead here.

I also wanted to make this a little more "techish" and not just "look how stupid I was yesterday"




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timatoe

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #4 on: November 08, 2014, 02:33:20 PM »

You getting this thing ready to tow your Jeep to Moab?
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #5 on: November 08, 2014, 05:16:27 PM »

Trying to.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #6 on: November 08, 2014, 05:16:51 PM »

I need to replace the airbags next.
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timatoe

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #7 on: November 08, 2014, 07:33:32 PM »

Right on.  I want to add some air bags to the motor home before that trip, we'll see if I can just get it ready before then.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #8 on: November 09, 2014, 06:49:41 AM »

Mine has the airbags but I think they rotted out or one has a hole or something.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #9 on: January 04, 2015, 10:48:48 AM »

After fixing the reverse lights I determined that I still can't see shit out of the back of my truck. I decided to buy two of these from amazon to see if I could get some extra light back there. I will follow up with more details when I install them.
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Screaming Bear

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #10 on: January 04, 2015, 11:36:21 AM »

I'm interested. I was thinking of adding a cheap SR12"on top of my winch for fill in, but a pair of small lights might be more police friendly.
My Truck-Lite LED headlights are bright but have a choppy pattern. If I spend too much I would feel I should have just bought the top shelf Speaker Evolution 2's.

Did you get your trans cooler and brakes done?
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51 CJ3-A, 4.3 TBI Chevy, SM420, Dana 18TC, 30/44 Full Floaters, Yukon Front Axle and Hubs, rear drive flanges, Detroit Fr / E-Locker Rr, 4.27:1 Gears, 74:1, HD steering / 4 wheel disk brakes, Viair 550C, 100% LED - VisionX headlights, Rigid Light-bar, DOT Fogs, Grote tail, Soft Top and Heater, 35"KM-2's, 3" up, no articulation - it works

pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #11 on: January 04, 2015, 03:01:19 PM »

Signstek 2*18W CREE LED Flood Light Headlight Work Light Lamp off Road High Power ATV Jeep 4x4 Tractor off Road Light Fog Driving Bar Rree Truck SUV Car IP67 Waterproof Dustproof Shockproof (Black) https://www.amazon.com/dp/B00GLLW3AM/ref=cm_sw_r_awd_vxCQub199197R
Here are the ones I bought.
I had the brakes bled and they seem okay now. I still need to do the airbags and the tranny cooler but I've been lazy.
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timatoe

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #12 on: January 04, 2015, 09:51:11 PM »

Get the biggest cooler you can fit, they're cheap.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #13 on: January 08, 2015, 05:32:08 PM »

Do you recommend putting it in the grill or under the truck somewhere?

I looked and my truck has 6 ports going to the radiator. Coolant, transmission, and engine oil. How common is that?

I also replaced the air springs in the back today. It rides so much better now.
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timatoe

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #14 on: January 08, 2015, 09:46:59 PM »

I've never seen engine oil go through the radiator.  I'd put it in front of the radiator, with the fluid going into the radiator then out to the cooler then back to the return line, if that makes sense.  Depending on the size of the cooler you may also gain a quart or more fluid.
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CJ-5 Renegade

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #15 on: January 08, 2015, 10:43:07 PM »

Yep that's  what they did back then with the  oil cooler. My 89 was that way also. Another thing that you might want to consider is replacing the  plastic sided radiator with an all metal 4 core one if you haven't done that already.  Got mine from auto zone, called the heat buster. Just barely fit, but made
Big difference especially in the summer when towing heat gauge never moved even when I ran the air conditioner.
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pdangerp

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #16 on: January 12, 2015, 10:24:24 PM »

I went ahead and reserved my club trailer so I can tow the jeep. I need to get a trailer brake controller now.
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Mr.B

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #17 on: January 13, 2015, 05:41:39 AM »

In the interest of preparedness, could you tow the truck on the trailer, with the Jeep?
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White '94 YJ 2.5L 5 speed, 35" BFGs KM2's, 5" lift, Mark VII 2 speed fan, Milemarker PE8000, Front Aussie Locker, Power steering conversion, '98 Cavalier seats, MORE Boomerangs in front, 136 amp ZJ alternator, JB conversions SYE, Tom Woods custom drive shaft, 8.8 with ARB, 4.88 gear ratio, Teralow

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Sccafire

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #18 on: January 13, 2015, 08:32:16 AM »

He could but would not get to far
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Scott

timatoe

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Re: 1991 Chevy c1500 electrical troubleshooting
« Reply #19 on: January 13, 2015, 09:17:52 AM »

How heavy is the trailer?  Understandably the trailer having brakes is better than flat towing without a braking system, but overall weight etc, I'd lean toward flat towing (of course there's the cost of a supplemental braking system at that point though).
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