1979 GMC van FUSE BLOCK diagram????

[Wishiniwuzfishin]

Anybody have any idea where I can find a diagram of the fuse block of a 1979 GMC Vandura van? I imagine some previous and later years and probably trucks would be the same if I could find any close to 1979 also.

I dont have the owners manual.

Thanks

[dolluper]

Re: 1979 GMC van FUSE BLOCK diagram????

Going from memory here so bare with me....on the right side lower IP panel for guages there is a relay....behind on the guage cover that is ,,,it's used not to screw guages when starting.....could be different location it was a while ago I worked on one of these LOL's ...so far your tracking down is paying off ...so don't give up your doing good

[Wishiniwuzfishin]

Re: 1979 GMC van FUSE BLOCK diagram????

Just got done checking the fuse box out and I'm starting to think all the non-working things are not related. Every test I did in the fuse box checked out ok.

And I found out the blower motor connector on the motor itself under the hood was off. Plugged in back on and blower is working.

Guess I'll start looking elsewhere besides the fusebox.

[Wishiniwuzfishin]

Re: 1979 GMC van FUSE BLOCK diagram????

It is the factory AM-FM radio. I haven't seen where any wiring has been cut into or spliced. Everything I have seen so far looks normal.

Not working:

Oil pressure, temperature, and voltmeter gauges

Heater blower motor

Radio....no power

Cruise

That's what I know of that is not working.

Working: Fuel gauge, Dome light (with both headlight switch knob and door jamb switches), All exterior and driving lights (stop, tail, turn etc), Inst. Panel lights, Wipers, ......haven't tested horn.

I pulled all fuses from fuse block...all were good.

My next step is to put a voltmeter into fuse terminals in fuse block for connections for gauges, blower motor, and radio fuses to see if they are getting power from the fuse block.....then jump the blower motor connections to see if the blower motor itself is working.

EDIT: Horn also works

[dolluper]

Re: 1979 GMC van FUSE BLOCK diagram????

Give us a list of whats not working....me thinks someone did some wire butchery....no power to guages cut spliced wire to add something or an in line fuse.....radio probably....not stock one eh

[RogersJetboat454]

Re: 1979 GMC van FUSE BLOCK diagram????

My key switch is on the dash, not the steering column. I think it's OEM but can't say 100%

Yes I tried the ACC position also...no change.

Hmmm...
Guessing the company that converted the chassis to a motor home musta done that. Pretty much every GM car and truck from that era had the same Saginaw steering column that worked like I described.

Still could have issues with your switch...

[Wishiniwuzfishin]

Re: 1979 GMC van FUSE BLOCK diagram????

My key switch is on the dash, not the steering column. I think it's OEM but can't say 100%

Yes I tried the ACC position also...no change.

[RogersJetboat454]

Re: 1979 GMC van FUSE BLOCK diagram????

I know where to put the key in. I assume the contacts on it are what you are talking about.

Could bad contacts be causing my problems?

I guess I should put a voltmeter on the fuse box and see if I'm getting power to the individual circuits that aren't working. That would be easier than trying to check the key switch.

The ignition switch is not part of the ignition lock, it is further down the "tree". The lock cylinder has a rod coming off it that goes down the column to a big honking plastic switch mounted on the top or side of the column. When you turn the key to its different positions, that in turn causes the rod to move the switch to its different detents (ACC,Stop,Run,Start). I have seen these switches fail before. Just outa curiosity, have you tried turning the key to the accessory position (from the key in the stop position, twist it back wards toward you) to see if anything works then?

[Wishiniwuzfishin]

Re: 1979 GMC van FUSE BLOCK diagram????

I know where to put the key in. I assume the contacts on it are what you are talking about.

Could bad contacts be causing my problems?

I guess I should put a voltmeter on the fuse box and see if I'm getting power to the individual circuits that aren't working. That would be easier than trying to check the key switch.

[RogersJetboat454]

Re: 1979 GMC van FUSE BLOCK diagram????

dome light works with door jamb switch...... I/P lights work........also forgot radio and cruise don't work.

Couldn't read most labels on fuse block but I pulled all of them and all were good.

I guess it's possible that everything that doesn't work is not related.....just don't work

Guess it wouldn't be unusual for blower motor, cruise, and radio to not work.......but temp, oil pressure and voltmeter all not working seemed odd.

Going to try and jump blower motor tomorrow....not really concerned with radio or cruise.......but would like to get gauges working.

Any more ideas?

What about the big honking 33 year old ignition switch you mentioned before? It's not out of the realm of possibility that the contacts inside are shot. You know where it is, right?

[Bob_VT]

Re: 1979 GMC van FUSE BLOCK diagram????

The diagram should not be too far off of this http://www.elcaminocentral.com/articles/wiring/811.gif

Try google images.

[Wishiniwuzfishin]

Re: 1979 GMC van FUSE BLOCK diagram????

dome light works with door jamb switch...... I/P lights work........also forgot radio and cruise don't work.

Couldn't read most labels on fuse block but I pulled all of them and all were good.

I guess it's possible that everything that doesn't work is not related.....just don't work

Guess it wouldn't be unusual for blower motor, cruise, and radio to not work.......but temp, oil pressure and voltmeter all not working seemed odd.

Going to try and jump blower motor tomorrow....not really concerned with radio or cruise.......but would like to get gauges working.

Any more ideas?

[dolluper]

Re: 1979 GMC van FUSE BLOCK diagram????

If dome light + IP lights don't work it's a sure sign the door switch not grounding or is faulty....be very carefull if you remove them 2 wires on back can fall off infin you don't hold your head right LOL's ..best to disconnect the battery....if wires fall off your going to be removing kick plates and more to get at them a pain....just look where the switch installs in door frame if rusty good chance it's not grounding and the problem....clean up and reinstall
One other place to check if multiable electrics not working is the fuseable link by the starters main bolt there should be 2 located there on heavy red wires

[RogersJetboat454]

Re: 1979 GMC van FUSE BLOCK diagram????

PM sent Wish.

[Wishiniwuzfishin]

Re: 1979 GMC van FUSE BLOCK diagram????

Thanks for the replies guys. Actually the vehicle is a class C 24ft motorhome, built on a GMC 1 ton Vandura chassis. From the front seats forward it is basically the same as a regular 1 ton van.

Previous owner told me about the gauges not working......I discovered the blower motor issue while driving it home.

I was just looking for the easiest way to troubleshoot. Might have to get in there under the dash with a voltmeter.... and I'll check out the dome lights today.

Any thing else I might look for? I read something online.........if I understood it right.......that some parts of the fuse block get there power thru the ignition switch. Issues with it might be causing the problem. The key switch works fine for starting it up and haven't noticed anything except what I mentioned.

Fuel gauge definetely works....put some gas in it.....needle moved up.......drove it home....needle moved down.

Not sure about IP lights. Drove it home in daylight so I didn't use headlights.