JamesW

No... the speedo is mechanical. The Alt gage is wired differently.. Neither of these use the ground that the others do. This ground usually is attached to the screw that holds the CVU mounted to the metal back of the dash.

halsted

I've taken down cluster panel. Black wire to CVR screw down does not look corroded and feeds into wiring harness. How do I test groung to cluster panel? Again, problem is fuel, oil, temp gauges as well as cluster light, do not work.

Clu7ch

That's the fun part!

You say the ground wire to the cluster is visibly good, no corrosion or fraying? I would say your best bet at this point would be to try the regulator itself.

halsted

The wire I'm talking about goes to the screw holding down the CVR. I don't know if there is another separate ground to the entire cluster panel. Regarding CVR, using a meter( although electronics is not my forte) I got voltage going into CVR and what appears to be less voltage coming out. I think this suggests CVR is ok. They're about $40. I could replace, but I would prefer to rule out other stuff.

Clu7ch

I can't say I blame you for not wanting to spend the money. I wouldn't either.

I don't know what the output levelshould be regarding the regulator.

The only things that I could see that would cause this problem would be, frayed/corroded/split ground, bad CVR, bad fuse, bad cluster (probably the least common), frayed/corroded/split wiring coming from the reg under the hood (a fray between the CVR and VR under the hood).



Or you could just be that unlucky and have all of the lights blown and bad gauges.

I can't think of anything else that would cause a problem like you are describing.


You've eliminated the ground wire, so that's one off the list. Try the fuse panel next. Check the output at the VR under the hood. Check for any visibly damaged wires between there and the CVR (have fun with this one). Just for s$%#s and giggles, check the bulbs in the cluster itself. You never know when you really are unlucky. If it's not any of these,I would highly recommend either getting a new CVR or not driving past dusk.

jlg2002

IRT my 66 shop manual, the temp, oil and fuel gauge recieve an average 5.0 vdc from the CVR. the CVR ground wire termination point (blk) is suppossed to be on a bracket behind the inst cluster opening, ign switch sideand it's combined with the wiper ground Blk wht. My advice, remove both ends and burnish the attach points. You can also check for the 5 vdc at each of the gauges you've listed once you've established you have good power and ground at the CVR.
good luck!

tarafied1

I have had some issues recently with my IVR too. When you check it out, the output voltage will not be a constant 5 volts but a pulse and should (as was said) average 5 volts. There is a screw on the IVR that you can adjust if the IVR is not putting out full voltage. The cluster on the 67/68 ground thru the dash screws, there is no seperate ground wire. I don't know for sure on the and earlier cars. On the IVR there is a terminal marked IGN which should read battery volts and the other lead is the pulsing volts for the gauges. You can confirm the gauges function by grounding the lead from the sending unit. The gauge will jump to full reading, don't leave it grounded long. This will confirm wiring and gauge is okay. If your engine block ground wire is bad or missing, the gauges will not work well either, the sending unit is basically grounding the gauge by varing the resistance as temp, fuel level or oil pressure changes. If the engine itself is not grounded well that won't help.
The instrument lights do have a very small fuse and can blow quite easy, as has been said it is not related to the IVR.

kalli

just a word on the speedo cable. it's quite easy when you know how to do it (have done it ten times).

when you untighten the nut to pull the plastic cable with its inner wire out of the speedo it happens a lot that you pull this metall inner wire a bit out of the plastic cable. which means you pulled it out of the gear in the gearbox that drives this cable.

So before your're putting it back on, check if you can turn the metal wire in the cable. If you can without resistance then this is what happened to you.

push it back into the plastic cable in a turning motion so you have it back in the gears on gearbox side.
you won't be able to turn it anymore and it should stick out only by lets say 3 mm from the nut. don't be afraid, you can't push it too far.

when you have that it should be quite easy to put the njut over the cluster and tighten it. only a bit wiggling needed then.

wrong (wire pulled out of gearbox drive):

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OK (wire is fully seated in gearbox drive and the end will fit into the speedo):

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you'll get the feeling for it, the more often you do it, the easier it'll get ....