Hello,

I am struggling to chase down this electrical issue on my 71 Olds Cutlass Convertible. I was driving one day and the car died. After investigating, I found that the main starter wire had grounded out against my headers. I took it all apart, bought new battery and starter, and rerouted wires away from headers. Got in to start it and...nothing! No dash lights, no clicking, no head lights. The horn and the top motor work though, so I started testing components and found that I had no power to the fuse box. I also ran 12V directly to purple wire going to the starter and it cranked up. That tells me that both my starter and my ground should be good. I have over 12V going through the fusible link, and 12V to the orange wire on the firewall which I believe powers the fuse box, but no voltage to any fuses. Because there is direct power the fuse box, I didn't believe there was a component that could fail and kill power to the box. Maybe I am wrong though, could the ignition switch or neutral safety switch cause this? or maybe the voltage regulator or module in the HEI? I tend to think not, but any help would be greatly appreciated.

 

Check the fusible link that's in line with the wire that runs first to a splice and branches to the fuse box from the horn relay, it has a black end on it at the horn relay.

 

I have added a couple of videos so you can see whats happening, and the tests ive run.

Video 1: Video 2:

 

Check dimmer switch for corrosion.

 

My money is on the fusible link. You have bypassed around it with your jumper wire.... Tedd

 

I don't know what additional wiring has been added to your car. If you look at the wiring diagram there is a fusible link that comes off the horn relay. You need to find that wire and see if the fusible link is bad. The circuit breaker you checked thinking it supplies power to the fusebox does not exist in the original wiring, it may be for the convertible top.

 

My fusible link is running from the horn relay to the wire identified in the pic. Is that correct?

 

I have a 1971 CS convertible. I just went outdoors to grab a couple pictures for you. I need to review them and transfer to my PC. Before I do this and before I review my CSM, is the picture you posted upside down?

 

No sir, the picture is straight...

 

I think your VR is mounted upside down.

 

I think I might need to get another picture and re-evaluate my fusible link and wires off the horn relay just to be certain. I haven't had to work any issues regarding my fusible link. I have had to re-work some interior lighting on the car after I purchased it, but nothing regarding my fusible link (and I have removed my starter, solenoid, R&R coil, pulled distributor and rebuilt it, etc.). But, never had to evaluate my VR and/or the fusible link. At any rate, note my VR (below) and your image for discrepancies. I'll recheck my wiring just to be certain.

EDIT: OK, so I updated the image and I'll have to check what that thing which looks like the VR really is.

 

No. That's not the fusible link I have depicted. I'll post a picture of my fusible link. But, your VR is mounted upside down.

 

That is not a voltage regulator.

 

Is that the horn suppression thing? What is that thing Kenneth?

 

I think oldcutlass pegged it.

 

So according to the wire diagram, which wire would run power to the fuse box? My fusible link is showing 12V. Maybe whatever that is thats its plugged into on the firewall is causing the problem.

 

Here is my fusible link. I believe it's the original - not sure. Anyways, it runs into the plastic braided wire loom. I haven't change its routing other than ensured it ran down through the (+) battery cable tie when I removed the starter to change the oil pan gasket.

 

Images of that box which looks like a VR on the firewall and the black wire which routes directly from the horn relay post into that aluminum box.

 

yes, that is exactly where mine goes too. Im getting 12v at the black wire in the harness. If that is what powers the fusebox, I should have power. Should the purple wire in that harness get 12v too? Mine is currently getting no power.

 

I'm having to learn as I go here. I found one very small piece of the puzzle though. That aluminum box is a simple relay. It's contained in the Factory Assembly Manual.

 

FYI, this is the voltage regulator.

https://classicoldsmobile.com/forums...-144560/page2/

 

Again, that relay does not power the fuse box. There is a red wire that runs through the bulkhead connector that has a fusible link connected to the horn relay power stud. Look for this wire.

 

As Eric indicated in Post #2 red wire w/ black end you can visualize my fusible link in Post #17 - follow that wire. It should branch/splice. I believe I have captured the essence of which Eric is referring in the wiring diagram.

 

In the first video you posted (above) at 40 seconds that is not your fusible link (which I believe you know by now). There should be a 30amp fuse in there if I'm not mistaken.

 

At 1'12" in your first video you touched the left hand pole of the circuit breaker and you read 12.6V and believed it to be correct. That is a circuit breaker. Did you test the right hand pole of that circuit breaker demonstrating current was in fact able to pass through the circuit breaker?

 

yes sir, i did test the right hand side as well.

 

That circuit breaker has nothing to do with your issue, see post #23.

 

Dallas - At this point, can you say you have found the actual fusible link wire which is attached to the horn relay JB (Junction Block)? Someone prior to yourself may have installed something which looks entirely different than the one I posted and may have removed the fusible link portion of the wire. You might remove each of those wires from the JB and test each of those wires independently to determine which one might not be providing current right off the JB.

 

Update: All who said fusible link were spot on. I couldnt see the fusible link because i ran it from the horn relay block through the gap between my wheel well and fender. So I went to the firewall, identified the red wire and started pulling. Immediately there was no resistance so i kept pulling and this is what I found at the end.... Thanks for all your help guys!

 

So, I can't tell completely but appears someone replaced the original fusible link since I cannot determine exactly what's going on with the wire you're holding. At any rate, hopefully you're reviewing how to make a fusible link. I'll provide you a couple links (1) for creating a fusible link and another (2) for the wire size dimensions to create a fusible link. I'll have to look the wire size chart but it's generally going to be on the order of whatever the normal wire size is (look at the wiring diagram) you will create a fusible link I believe two gauges higher than normal wire size. So, if the normal wire is a 12 AWG you'd create a fusible link piece two gauge sizes higher (thinner), say 16 gauge. I'll try to find the chart or you can look it up yourself. They do, in fact sell fusible link wire - it has a thicker insulation wrapping than normal wire of the same gauge to reduce the chance of fire (albeit thicker insulation).

Your fusible link would be a short piece of wire off the JB (unlike the link below) but the creation of the fusible link is the same:

 

Reviewing the wiring diagram it demonstrates the fusible link is black 16 AWG and the remaining length of wire is red 12 AWG. As I suggested, the 16 AWG should be of a thicker insulation than a normal 16 AWG wire - this to prevent the black 16 AWG from burning through the insulation to reduce the chance of catching fire. Review the wiring diagram. My black 16 AWG fusible link is ~6" in length off the JB.

 

Thank you guys, I will certainly add the fusible link.