grounding a blazer - The 1947 - Present Chevrolet & GMC Truck Message Board Network

THENEWMEXICAN · 03-01-2010, 04:43 AM

So I’ve been reading reply after reply about the importance of a properly ground electrical system and NEED some pointers. I bought a '70 Blazer with some wiring issues (nothing but the headlights worked) but after 4hrs in the truck I got all the lights to work... kinda.
Here is where I’m at:
1. The gauges work but not the backlights or indicators
2. Headlights, Hazards, Markers, Parking and Brake lights work or atleast turn on.
3. Only the passenger tail (light) turn signal works. (nothing else blinks) Hell, I don't even know what is supposed to blink when I flip the turn signal.
4. All fuses and bulbs are good. flashers too.

I guess I’m cleaning house on bad wiring and looking for some tips on grounding. And if anyone knows of a better set of wiring diagrams (all I have is the generic Haynes manual) I’d really appreciate the help. Getting the turn signals working by mid week so I could start looking for other problems is my goal. And is there reason i should start blaming the switch and not the grounds?

**Yukon Jack** · 03-01-2010, 11:14 AM

Go to the FAQ section and there is an index that contains a link to wiring diagrams.

I hate wiring/light problems! There should be a engine block to frame ground and then a number of grounds from the body to the frame in various locations. I'd make sure the bulb sockets are clean by hitting them with a little sand paper. I've got a short somewhere in my system that I can't locate and I'm about ready to buy new harnesses and start fresh!

67chevy2wd · 03-01-2010, 11:43 AM

I would check to see if you have power at the sockets. If not then don't go looking for a ground issue. Maybe use a paper clip to see if you are getting power at the connector under the steering column coming from the blinker switch. Also try the hazards and see if they work. Could be something as simple as the flasher control on the fuse box (can't think of the correct term. Just got home from a midnight shift and I have been up for 21 hrs straight so it is time for bed) I hope I helped some.

67chevy2wd · 03-01-2010, 11:54 AM

Probably not the easiest to see but here are the wiring diagrams.

Engine
http://i149.photobucket.com/albums/s...tandFrontL.jpg

Cab and tail lights
http://i149.photobucket.com/albums/s...BulkheadCo.jpg

fun in dirt · 03-01-2010, 12:25 PM

Sounds like not good contact with or something messed up on that circuit sheet to the back of the gauge cluster. (Oh yeah, but first make sure that your cluster back is grounded to the dash well.) I fought this same stuff with my lights for several weeks after got my blazer. Then finally gave up & ditched the circuit sheet. Went to Radio shack & got some little green lights for the blinkers, blue for bright headlightsand others for normal backlights. Then cut the plug off that went into the cluster & wired each directly to each bulb - no problems since!

THENEWMEXICAN · 03-02-2010, 04:41 AM

I ran some more tests on the system today while doing an inventory of parts I'll be replacing before I hit to road and still no reverse lights, and the only functioning turn signal is the passenger tail... (literally everything Heads, Brakes, Hazards-brights and dims-, Markers, and License Lamp work) anyway:

Yukon – I have a whole Ron Francis wiring kit awaiting my frustrations to reach their peak. (the thing was supposed to go in the mustang but why fix something that isn’t broken right?...) and I’m not done fighting either.

67 – Thanks for the diagrams! And good looking out on the switch call, tonight a guy at work said the same thing. I’ll keep you posted on what I find tomorrow or the next. I’ve already replaced and switched the flashers and the Hazards work fine…

Fun – Good call on the missing link in the circuit: I Found a missing bulb and a little corrosion. I’m going to remove the cluster tomorrow and check out the circuit more in-depth. A new printed circuit is on my list of stuff to buy to to ease my fears of future problems anyway.

Side question:
I also have a random gray wire coming down from my steering column and going nowhere with a spade terminal… any idea what this thing is for?

67chevy2wd · 03-02-2010, 11:12 AM

Quote:

Originally Posted by THENEWMEXICAN

Side question:
I also have a random gray wire coming down from my steering column and going nowhere with a spade terminal… any idea what this thing is for?

What kind of steering column is in your blazer? I just installed a van tilt column in my 71 GMC and it had a gray wire witch was a power wire for the illumination of the PRND21 indicator.

THENEWMEXICAN · 03-02-2010, 01:30 PM

Quote:

Originally Posted by 67chevy2wd

What kind of steering column is in your blazer? I just installed a van tilt column in my 71 GMC and it had a gray wire witch was a power wire for the illumination of the PRND21 indicator.

stock tilt for the '70.

**jaros44sr** · 03-02-2010, 01:39 PM

Quote:

Originally Posted by 67chevy2wd

What kind of steering column is in your blazer? I just installed a van tilt column in my 71 GMC and it had a gray wire witch was a power wire for the illumination of the PRND21 indicator.

^^^Yep, I believe he's right^^^

soverstreet · 03-02-2010, 11:47 PM

i had issues with the blinking side of my 71. found all the contacts in the steering column needed a really good cleaning and degreasing after 40 years and they all started working again. also look at the wiring to the gauge cluster. some people see the 3 gauge cluster and really have it wired for the other and the wiring is not the same and screws up alot of stuff!

THENEWMEXICAN · 03-05-2010, 04:36 AM

sover- there was some slight corrosion in my directional signal connector that needed some tlc from some sand paper.

Well guys, after further inspection of my steering column I have realized that mine is not 67-72 tilt steering column but one which at one point had some sort of 4-terminal plug/socket near the firewall… (like my buddy’s 79 c10 has)
And after cleaning up all the contacts, including all the cluster bulbs and one more time I got all my blinkers to work except my driver-side front. (I’m double-checking the grounds tomorrow. Again.) … On the plus side that one blinker is the only thing holding me back from being completely street legal.
But my light for my PRND indicator light is busted so testing it is going to be an issue for later. Figuring out why the horn doesn’t work will be my last priority.
I'm almost there.

**Tom Vogel** · 03-05-2010, 10:34 AM

If thats your 70 in your avatar, its looks Nice.

THENEWMEXICAN · 03-08-2010, 04:36 AM

TOM- thanks! everyone who takes a good look at everything really enjoys it

67 and jaros- i replaced the prndl bulb and plugged a random gray wire (that was hanging down my steering column)into my fuse box => prndl/gear indicator illumination... thanks for the help

sover- your last comment came a week early cause now that i'm getting deeper into my electrical there is a huge possibility that some of my wiring with the gauges isn't right... or at least doesn't look right. i can't figure out the installation whos or whens a few gauges including the tach... you were right, more research is in order.

update: took a 125 mile test drive to show the family mechanic the blazer and guess what light decided to start working? the front driver turn. leave it to the last of my problems to work itself out miraculously when we were going for a joy ride. but the tach stopped moving past 20 (2000k) during the same joy ride so not everything was gravy. BUT he did inform me that due to some equipment and wiring mods the previously id'd 4terminal/plug/socket at the bottom of my steering column near the firewall is the reason i don't have backup lights... anyone have them wired up differently or at least without the use of that plug?

03-01-2010, 04:43 AM	#1
THENEWMEXICAN Registered User Join Date: Feb 2010 Location: Albuquerque NM Posts: 28	grounding a blazer So I’ve been reading reply after reply about the importance of a properly ground electrical system and NEED some pointers. I bought a '70 Blazer with some wiring issues (nothing but the headlights worked) but after 4hrs in the truck I got all the lights to work... kinda. Here is where I’m at: 1. The gauges work but not the backlights or indicators 2. Headlights, Hazards, Markers, Parking and Brake lights work or atleast turn on. 3. Only the passenger tail (light) turn signal works. (nothing else blinks) Hell, I don't even know what is supposed to blink when I flip the turn signal. 4. All fuses and bulbs are good. flashers too. I guess I’m cleaning house on bad wiring and looking for some tips on grounding. And if anyone knows of a better set of wiring diagrams (all I have is the generic Haynes manual) I’d really appreciate the help. Getting the turn signals working by mid week so I could start looking for other problems is my goal. And is there reason i should start blaming the switch and not the grounds? Last edited by THENEWMEXICAN; 03-01-2010 at 04:43 AM.

03-01-2010, 11:14 AM	#2
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	Re: grounding a blazer Go to the FAQ section and there is an index that contains a link to wiring diagrams. I hate wiring/light problems! There should be a engine block to frame ground and then a number of grounds from the body to the frame in various locations. I'd make sure the bulb sockets are clean by hitting them with a little sand paper. I've got a short somewhere in my system that I can't locate and I'm about ready to buy new harnesses and start fresh! __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

03-01-2010, 11:43 AM	#3
67chevy2wd Registered User Join Date: Sep 2003 Location: New Salem, ND Posts: 1,558	Re: grounding a blazer I would check to see if you have power at the sockets. If not then don't go looking for a ground issue. Maybe use a paper clip to see if you are getting power at the connector under the steering column coming from the blinker switch. Also try the hazards and see if they work. Could be something as simple as the flasher control on the fuse box (can't think of the correct term. Just got home from a midnight shift and I have been up for 21 hrs straight so it is time for bed) I hope I helped some. __________________ 07 Chevy classic LBZ Duramax (a few mods) '67 Chevy 1/2 ton 2wd (in pieces) '69 Chevy 1/2 ton 2wd (on hold) '71 GMC 3/4 ton 4x4 ‘71 GMC 1/2 ton 2wd suburban

03-01-2010, 11:54 AM	#4
67chevy2wd Registered User Join Date: Sep 2003 Location: New Salem, ND Posts: 1,558	Re: grounding a blazer Probably not the easiest to see but here are the wiring diagrams. Engine http://i149.photobucket.com/albums/s...tandFrontL.jpg Cab and tail lights http://i149.photobucket.com/albums/s...BulkheadCo.jpg __________________ 07 Chevy classic LBZ Duramax (a few mods) '67 Chevy 1/2 ton 2wd (in pieces) '69 Chevy 1/2 ton 2wd (on hold) '71 GMC 3/4 ton 4x4 ‘71 GMC 1/2 ton 2wd suburban

03-01-2010, 12:25 PM	#5
fun in dirt Registered User Join Date: Jan 2007 Location: Mississippi Posts: 2,122	Re: grounding a blazer Sounds like not good contact with or something messed up on that circuit sheet to the back of the gauge cluster. (Oh yeah, but first make sure that your cluster back is grounded to the dash well.) I fought this same stuff with my lights for several weeks after got my blazer. Then finally gave up & ditched the circuit sheet. Went to Radio shack & got some little green lights for the blinkers, blue for bright headlightsand others for normal backlights. Then cut the plug off that went into the cluster & wired each directly to each bulb - no problems since! __________________ '72 C to K20 "Cannibalizer" http://67-72chevytrucks.com/vboard/s...32#post8653432 '85 K30 "Big Nassy" [B]'85 C10 [B] "Corpse" '01 2500 Suburban ...party wagon & tow truck '06 Silverado SS...DD '06 C1500 WT...DD '07 Classic C1500 WT...DD Built & sold cause can't keep 'em all: '72 Blazer "The Bucket" http://67-72chevytrucks.com/vboard/s...d.php?t=433190 '55 Chevy straight axle gasser https://www.trifive.com/forums/showthread.php?t=173938 '69 Pro Street Chevelle http://www.chevelles.com/forums/showthread.php?t=332541 '86 M1031 CUCV http://67-72chevytrucks.com/vboard/s...d.php?t=553619

03-02-2010, 04:41 AM	#6
THENEWMEXICAN Registered User Join Date: Feb 2010 Location: Albuquerque NM Posts: 28	Re: grounding a blazer I ran some more tests on the system today while doing an inventory of parts I'll be replacing before I hit to road and still no reverse lights, and the only functioning turn signal is the passenger tail... (literally everything Heads, Brakes, Hazards-brights and dims-, Markers, and License Lamp work) anyway: Yukon – I have a whole Ron Francis wiring kit awaiting my frustrations to reach their peak. (the thing was supposed to go in the mustang but why fix something that isn’t broken right?...) and I’m not done fighting either. 67 – Thanks for the diagrams! And good looking out on the switch call, tonight a guy at work said the same thing. I’ll keep you posted on what I find tomorrow or the next. I’ve already replaced and switched the flashers and the Hazards work fine… Fun – Good call on the missing link in the circuit: I Found a missing bulb and a little corrosion. I’m going to remove the cluster tomorrow and check out the circuit more in-depth. A new printed circuit is on my list of stuff to buy to to ease my fears of future problems anyway. Side question: I also have a random gray wire coming down from my steering column and going nowhere with a spade terminal… any idea what this thing is for? Last edited by THENEWMEXICAN; 03-02-2010 at 04:41 AM.

03-02-2010, 11:47 PM	#10
soverstreet Registered User Join Date: Jan 2010 Location: houston, texas Posts: 12	Re: grounding a blazer i had issues with the blinking side of my 71. found all the contacts in the steering column needed a really good cleaning and degreasing after 40 years and they all started working again. also look at the wiring to the gauge cluster. some people see the 3 gauge cluster and really have it wired for the other and the wiring is not the same and screws up alot of stuff!

03-05-2010, 04:36 AM	#11
THENEWMEXICAN Registered User Join Date: Feb 2010 Location: Albuquerque NM Posts: 28	Re: grounding a blazer sover- there was some slight corrosion in my directional signal connector that needed some tlc from some sand paper. Well guys, after further inspection of my steering column I have realized that mine is not 67-72 tilt steering column but one which at one point had some sort of 4-terminal plug/socket near the firewall… (like my buddy’s 79 c10 has) And after cleaning up all the contacts, including all the cluster bulbs and one more time I got all my blinkers to work except my driver-side front. (I’m double-checking the grounds tomorrow. Again.) … On the plus side that one blinker is the only thing holding me back from being completely street legal. But my light for my PRND indicator light is busted so testing it is going to be an issue for later. Figuring out why the horn doesn’t work will be my last priority. I'm almost there. Last edited by THENEWMEXICAN; 03-05-2010 at 04:36 AM.

03-05-2010, 10:34 AM	#12
Tom Vogel 2WD Jimmy Join Date: Mar 2005 Location: Davis County, Utah Posts: 2,565	Re: grounding a blazer If thats your 70 in your avatar, its looks Nice.

03-08-2010, 04:36 AM	#13
THENEWMEXICAN Registered User Join Date: Feb 2010 Location: Albuquerque NM Posts: 28	Re: grounding a blazer TOM- thanks! everyone who takes a good look at everything really enjoys it 67 and jaros- i replaced the prndl bulb and plugged a random gray wire (that was hanging down my steering column)into my fuse box => prndl/gear indicator illumination... thanks for the help sover- your last comment came a week early cause now that i'm getting deeper into my electrical there is a huge possibility that some of my wiring with the gauges isn't right... or at least doesn't look right. i can't figure out the installation whos or whens a few gauges including the tach... you were right, more research is in order. update: took a 125 mile test drive to show the family mechanic the blazer and guess what light decided to start working? the front driver turn. leave it to the last of my problems to work itself out miraculously when we were going for a joy ride. but the tach stopped moving past 20 (2000k) during the same joy ride so not everything was gravy. BUT he did inform me that due to some equipment and wiring mods the previously id'd 4terminal/plug/socket at the bottom of my steering column near the firewall is the reason i don't have backup lights... anyone have them wired up differently or at least without the use of that plug? Last edited by THENEWMEXICAN; 03-08-2010 at 04:39 AM.



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