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#1
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Don't know where to begin
Yesterday I started up my 72 GTO, let it warm up and checked the timing. Decided to advance it from twelve to fourteen just to see if it would run better. Checked the vacuum and it's at about 19 inches. Closed the hood and go for a test drive. Less than a mile away from my house the car died, I mean TOTALLY died. Lost ALL electricity. So far, I see nothing that's melted down or looks of failure. I didn't find any blown fuses. I did smell SOMETHING that wreaked of electrical short, though it was very faint.
Any ideas where to start? I had Triple A flatbed he car back to my house. |
#2
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Did you have head light or starter still crank?
Start looking the harness over, something burnt up Is the car an automatic?
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Carburetor building & modification services Servicing the Pontiac community over 20 years |
#3
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check wire path to starter for crusty wires.
a classic for somebody ( not mee) has been the fuse block bolt being loose and the engine harness backed out.
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12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct |
#4
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Based on the title of your thread, the place to begin is at the beginning. Everything starts at the battery, so start there. First perform a complete visual inspection of the underhood electrical system. Battery cables, negative to the engine. Battery lead to the alternator and starter. Use a test light or a DVOM would be better. Should have 12.4V minimum to the ALT and starter main lead. Then check what does and does not work. If the entire electrical system is dead, no lights, no horn, wipers, blower motor, dash warning lights, it has to be one of the few main power or ground leads. If some stuff works and other stuff does not. report back so you can get some more direction. Good luck. It is almost certainly a SINGLE problem when many circuits go dead at once.
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#5
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I've had a couple of fairly new batteries totally crap out all of a sudden late. As he said check from the start.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#6
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Check the bulkhead connectors at the firewall in the engine compartment that attach to the fuse block inside the car. BTDT.
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Jeff |
#7
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Factory wiring harness?
I've seen fusible link wire blow out from old age. No short, no overload, just what they're made out of gets stiff, corroded and crusty. Just poof and they're gone for no apparent reason. Clay
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All the federales say,they could've had him any day They only let him slip away, out of kindness...I suppose Poncho & Lefty |
#8
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Thanks guys for your quick reponses. I just found the culprit that started it all. A splice in the 12v ignition wire to my HEI grounded against the dipstick tube. Still looking for the solution as I have NO electrical at all. The car is automatic, and, no the lights, horn, nothing electrical works. So my question now is what is the primary point of electrical distribution as I believe that's where the problem is. I have a 660 jump box that I hooked up after disconnecting the battery, and still no go.
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#9
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Check the fusible link wire. Don't know exactly where they're at on the 72.
Bolted down with the starter + cable Back of alternator At horn relay Should be one of those places. And they do blow out when you have a short Clay
__________________
All the federales say,they could've had him any day They only let him slip away, out of kindness...I suppose Poncho & Lefty |
#10
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Ok, just checked the bulkhead connector inside and out but saw nothing unusual there. Tomorrow, I will pull the starter and see if the battery cable has been compromised. Since that's the only place that the battery is directly connected to, the problem may lie there. I haven't been able to find any fusible links.
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#11
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It's a type of wire. The wire can blow out and the insulation stay intact. It'll stretch like a rubber band when it's blown.
Clay |
#12
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That 12V feed to the HEI that you found shorted is protected by a fuseable link as mentioned above. I am not sure where it is located. When you find it though, it is very important that you replace it with the same amperage fuseable link wire that it came with. Do not splice regular wire in it's place. Your only other option would be to replace that wire with a proper amperage in-line fuse which would not look stock but would provide protection. BTW, a REAL parts store like a NAPA or an independent should have fusable link wire. It's doubtful anyone under 40 at an Oreily's, AutoZone, AdvanceAuto or CarQuest will have any idea what you are asking for. You will just get the "year make model ritual followed by the blank stare". Good luck.
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#13
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Most of the fusible link type wiring is in the loom that connects to the alternator. Runs by the valve cover and intake. The main wire from alternator to the starter is the only source of power to everything usually.
(except the starter gets its power from battery cable, but the neutral safety wire needs 12 volts from the alternator wire to crank) It is usually a bunch of red wires soldered together a few inches back of the alternator. Have to take the loom covering off, tape maybe? plastic covering maybe? Probably be noticeable if it is there. (like burnt or melted)
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John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
#14
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P.S.
Had a battery cable come loose on starter on a power shift and it shorted out against header. Instant dead. Like around midnight out in country.
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John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
#15
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A BIG THANK YOU to all of you as you have given me tips that I would never have thought of. And I've owned this car since 1987 and thought I knew every inch of it. Since I probably should replace the entire underhood wire harness, would the new one include all these fusible links?
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#16
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Did you check the battery itself? I've had the same experience as Skip. Battery totally went dead for no apparent reason. No voltage at all across the battery terminals.
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---------------------------- '72 Formula 400 Lucerne Blue, Blue Deluxe interior - My first car! '73 Firebird 350/4-speed Black on Black, mix & match. |
#17
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I cant find a good location, but its between the starter and the alternator. Follow the wiring from the starter up to the alternator and it has the links spliced in, the RED wire coming out, ends up at the large wire at the back of the Alternator. The Fusible Links then go to the Bulkhead Connector.
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
#18
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Quote:
I've had to replace several that were bolted down with the battery cable on the starter solenoid. And like John said, you've got the ones behind the alternator that go inside the car. Different makes and models had them in different locations. But they are there to protect the whole harness in the event of a short. Several circuits don't go through the fuse box and rely soley on the fusible links to prevent total melt downs. Clay
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All the federales say,they could've had him any day They only let him slip away, out of kindness...I suppose Poncho & Lefty |
#19
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This is schematic for 72:
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John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
#20
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If you have access to a service manual, page 12-40 discusses location and replacement. I snipped the page for you and attached below. It says the link is a loop of smaller gauge wire along the driver side valve cover, where it breaks out near the alternator.
I hope the pic isn't too small to be functional. I also included the underhood wiring schematic that shows the link.
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"...ridge reamer and ring compressor? Do they have tools like that?" |
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