'71 w/Intermittent Electrical Power Problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

badpeanut · 08-24-2002, 08:40 PM

I have a '71 K5 Blazer with the original points ignition. Sometimes it acts as though there is an open circuit from the battery somewhere (no headlights, no courtesy lights, won't crank). The battery and its connections are good. I replaced the ignition switch thinking this was the problem. When it is dead I can't revive it, but if I come back another day sometimes it is okay.

What else should I look at? I'm beginning to think it is possessed...

Wes

lukecp · 08-24-2002, 09:23 PM

I have had the same problem on my '72 before. Once, i was driving along after dark, on a moonless night, and the whole truck just died. Motor stopped, no lights worked, nothing electric. I had to feel around and find my flashlight. Turned out that the wire that goes off the + battery cable, the 10ga lead, had fallen out of its connecter. The connecter was the little black box (about 1"x1") that is mounted on the passenger side fender, next to the battery. If you loose a connection there, everything will go dead because all the power in the truck goes through that point. I would check all the connections on that wire, and trace it all the way up to the alternator. Also, check for a bad ground somewhere. Bad grounds have been known to do some pretty weird stuff.

Gordo · 08-24-2002, 10:23 PM

I know you said the bat connections are good but if by chance you are using the after-market replacement cable ends that clamp onto your old cable many times folks don't think to check and clean both ends of that clamp, the bat end and cable end.

**Patch** · 08-25-2002, 02:14 AM

I've seen corrosion in a fuse panel cause an intermitant problem with all of the electrical. It also was causing some fuses to blow as well.....?????

*racedvl* · 08-25-2002, 09:04 AM

Check and clean all grounds!!!!

jay6891 · 08-25-2002, 09:45 AM

I agree with everybody. I've had the same problem as you and it was the terminal end on the passenger fender. I finally just bypassed it and installed a 50 amp fuse sodered in its place. Also having problems now with the fusebox corrosion. Had drivers door off for a couple of months while doing body repair and have been fighting the fuse box ever since. Truck was outside. My shop is my driveway. NO work when it rains.

Bob Hinz · 08-25-2002, 10:20 AM

Sounds like you have a bad ground. I would check the gound wire that attaches to the block. Take it off and check the wire and clean the block where the wire attaches. There should be another wire that comes off the ground terminal of the battery and attaches to the body. I would check that and clean where it attaches. Need to make sure you have a good metal to metal connection. You might have another wire coming off the block and attaches to the frame. I just check my 72 chevy and it looks like I don't have a wire from the block to the frame. Hope this helps.

badpeanut · 08-25-2002, 02:17 PM

Thanks everyone! It turned out to be the black terminal box on the passenger fender. I cleaned the connections, greased them, and added an externally toothed lock washer.

Wes S.

PanelDeland · 08-25-2002, 04:08 PM

Glad you found it.I had one more suggestion to add.I had a car in HS that would take a notion to not crank or anything once in a while.I spent months looking for the problem and replacing parts.I finally found that by using a jumper cable from the battery to the starter it would start.The cable had corroded inside the insulation and would make contact or not sometimes affected by the temp.

1967LWBstepside · 08-25-2002, 04:50 PM

Lots of good advice here. I've fought many similar battles a while ago but most of mine involved finding a short that would drain the battery (finally found it in the steering column).

One question: What does the black terminal box on the passenger fender do? It's been so long since I bypassed it that I forgot where it hooked to and what it did.

Thanks,
Mike

badpeanut · 08-25-2002, 07:33 PM

Someone can correct me if I'm wrong, but the black terminal box just looks like a convenient way to tie the power lead from the battery into the rest of the truck's harness.

Hooter · 08-25-2002, 07:41 PM

I remember when the wire came off the little box, while i was driving it came off, when it came off the voltage regulator suddenly didnt have any power going to it which caused a big voltage spkie in my electrical system, burned out quite a few lights and ruined my tach. now i learned to use fuses.

08-24-2002, 08:40 PM	#1
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,756	'71 w/Intermittent Electrical Power Problem I have a '71 K5 Blazer with the original points ignition. Sometimes it acts as though there is an open circuit from the battery somewhere (no headlights, no courtesy lights, won't crank). The battery and its connections are good. I replaced the ignition switch thinking this was the problem. When it is dead I can't revive it, but if I come back another day sometimes it is okay. What else should I look at? I'm beginning to think it is possessed... Wes Last edited by badpeanut; 08-24-2002 at 08:43 PM.

08-24-2002, 09:23 PM	#2
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I have had the same problem on my '72 before. Once, i was driving along after dark, on a moonless night, and the whole truck just died. Motor stopped, no lights worked, nothing electric. I had to feel around and find my flashlight. Turned out that the wire that goes off the + battery cable, the 10ga lead, had fallen out of its connecter. The connecter was the little black box (about 1"x1") that is mounted on the passenger side fender, next to the battery. If you loose a connection there, everything will go dead because all the power in the truck goes through that point. I would check all the connections on that wire, and trace it all the way up to the alternator. Also, check for a bad ground somewhere. Bad grounds have been known to do some pretty weird stuff. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

08-24-2002, 10:23 PM	#3
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	I know you said the bat connections are good but if by chance you are using the after-market replacement cable ends that clamp onto your old cable many times folks don't think to check and clean both ends of that clamp, the bat end and cable end. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

08-25-2002, 02:14 AM	#4
Patch Senior Member Join Date: Jul 2002 Location: Oak Harbor, WA Posts: 705	Fuse panel I've seen corrosion in a fuse panel cause an intermitant problem with all of the electrical. It also was causing some fuses to blow as well.....????? __________________ Patch

08-25-2002, 09:45 AM	#6
jay6891 Car Knocker Join Date: May 2001 Location: jefferson,arkansas Posts: 664	I agree with everybody. I've had the same problem as you and it was the terminal end on the passenger fender. I finally just bypassed it and installed a 50 amp fuse sodered in its place. Also having problems now with the fusebox corrosion. Had drivers door off for a couple of months while doing body repair and have been fighting the fuse box ever since. Truck was outside. My shop is my driveway. NO work when it rains. __________________ 68 c-10,91 sportside bed,350 .030 over,4 bolt,10-1 comp,2.05 intake/1.94 exhaust,1.6 Harland Sharp roller rockers,edelbrock rpm cam and intake w/750 carb, 700r4, 3.73 gears,Jacabbs Electronic Igntion w/Accel HEI distributer and super coil. ZR-1 roll pan, filled tailights. Blazer tank. Hidden hitch. 2 1/2" Flowmaster 40's. Parts bought but not installed>> ford 9" posi with disc. CCP front and rear lowering kit 4/5. Cab corners,foor boards,rockers, cab braces, Phatom grill, Painless wiring kit.

08-25-2002, 09:04 AM	#5
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	Check and clean all grounds!!!!

08-25-2002, 10:20 AM	#7
Bob Hinz Registered User Join Date: Aug 2002 Location: Maine Posts: 6	Sounds like you have a bad ground. I would check the gound wire that attaches to the block. Take it off and check the wire and clean the block where the wire attaches. There should be another wire that comes off the ground terminal of the battery and attaches to the body. I would check that and clean where it attaches. Need to make sure you have a good metal to metal connection. You might have another wire coming off the block and attaches to the frame. I just check my 72 chevy and it looks like I don't have a wire from the block to the frame. Hope this helps. __________________ Bob Hinz

08-25-2002, 02:17 PM	#8
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,756	Thanks everyone! It turned out to be the black terminal box on the passenger fender. I cleaned the connections, greased them, and added an externally toothed lock washer. Wes S.

08-25-2002, 04:08 PM	#9
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Glad you found it.I had one more suggestion to add.I had a car in HS that would take a notion to not crank or anything once in a while.I spent months looking for the problem and replacing parts.I finally found that by using a jumper cable from the battery to the starter it would start.The cable had corroded inside the insulation and would make contact or not sometimes affected by the temp. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

08-25-2002, 04:50 PM	#10
1967LWBstepside 'Heavy Metal' Redefined. Join Date: Mar 2001 Location: Starkville, MS, USA Posts: 107	Lots of good advice here. I've fought many similar battles a while ago but most of mine involved finding a short that would drain the battery (finally found it in the steering column). One question: What does the black terminal box on the passenger fender do? It's been so long since I bypassed it that I forgot where it hooked to and what it did. Thanks, Mike __________________ 1967 C10 LWB stepside, 250 engine, GM HEI, aftermarket A/C., Clifford Performance intake, Stovebolt split headers, Carter AFB 500, X-pipe & Dynomax Super Turbos, 1 piece custom driveshaft, cyprus bed wood & stainless bed strips. Starkville, Mississippi \| My Truck Page

08-25-2002, 07:33 PM	#11
badpeanut Not a bad nut after all.. Join Date: Dec 2000 Location: ND Posts: 1,756	Someone can correct me if I'm wrong, but the black terminal box just looks like a convenient way to tie the power lead from the battery into the rest of the truck's harness.

08-25-2002, 07:41 PM	#12
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,083	I remember when the wire came off the little box, while i was driving it came off, when it came off the voltage regulator suddenly didnt have any power going to it which caused a big voltage spkie in my electrical system, burned out quite a few lights and ruined my tach. now i learned to use fuses. __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life



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