Instrument Cluster Questions

Ok, so I've been through my FSM, and haven't been able to answer these two questions, and also done various searches here, and just generally through the googles....

1) What should the fuel level sending unit wire color be in the stock harness on my 1970 CJ5? I can't find anything definitive anywhere (If there's a list of wire colours in my FSM, I've yet to find it. (and No, it's not a Haynes Manual =P)). It appears to be a yellow colour back at the sending unit itself. (I put a new sending unit in a few months back, and just getting around to troubleshooting as to why the fuel gauge doesn't work.

2) Does anybody have the part number for the single wire light sockets on the instrument cluster? (i.e. the one that is used on the Hi-Beam, Amps, and Oil Pressure warning lights?) I can't seem to find that one anywhere, and I'm missing one.

 

Excellent, thanks Howard.

 

I have a few extra sockets, pm me your address I'll send you one

 

Sweet. PM Incoming.

 

OK, so this isn't making any sense. I have continuity on the whole fuel level circuit, and a verified good ground from the sending unit to the frame. I have 12VDC across the instrument voltage regulator to the fuel gauge stud. Where could this be going wrong? It's a new gauge cluster and sending unit....

 

Dropped the tank and pulled the sending unit, using a multimeter, I should see the resistance change as I sweep the arm back and forth, yes?

 

Yes, whatever the TSM says the range is, like from 10 to 80 ohms and back. From the base/body of the sender to the threaded post.

 

Yeah, something's rotten in the kingdom of Denmark.....

Where did you find that Ohm measurement in the FSM? I couldn't seem to locate it in mine....

 

I don't have a '70 manual, but in the '72 manual it's in Section 3 - Electrical in an inset table about 40 pages in. E 72, 1/2 23 and F 9.

 

Where are you reading the 12vdc? If you have your meter probes (one on ground at the speedo housing) and (one on the fuel gauge stud) that the voltage regulator is connected to, you should be reading a pulsing 5 to 6 volt DC. If you are not getting any reading then you don't have the speedo housing grounded. You did not say where you were putting the ground probe for the meter to read 12vdc. It makes a diff.

I am assuming you have an external voltage regulator. Some external voltage regulators require the case to be grounded also.

 

I've pretty much concluded that I've got a bad fuel gauge.... I think. If I run a wire off the stud that the fuel sender should connect to on the fuel gauge, and just ground it, the gauge *should* read "Full", according to my FSM, and I get nothing.


Which is really annoying, this gauge cluster was NIB, came with the jeep when I bought it in a box of parts... Oh Well.

 

Ok, so I've definitely got the "wrong" gauge cluster for my '70. As it has turn signals in it, and I don't think a '70 would.

In any case, it's a VDO gauge, marked
VDO
S-2696
115.072.005X

The individual part numbers listed on the Temp and Fuel gauges are:

3331 TEMP
3332 FUEL

So far, I haven't been able to run down any information on the VDO replacement cluster directly, but that link you just gave me might allow me to get some testing done.

 

So yep, by all accounts, teh fuel gauge is shot. Something must have caused a short, with the old sending unit. Already got a fresh one ordered up.

 

Maybe too late, but MY NIB gauge cluster for my 1972 came with a screwed-up gauge too. Worth looking at: the bimetallic element within the gauge (accessible from the face) is a strip that takes a 90-degree turn outward (toward the viewer). This tab inserts into a slot in the pivoting plastic base to which the needle is friction-fit. As the strip changes shape with temperature, the tab moves in the slot, waving the needle around where you can see it. The end of that slot is a tiny plastic clip. Mine was open, detached from the tab. 30 seconds with forceps rectified the situation.

 

Yeah, it failed every electrical test that I was able to come up with, from the googles and the forum, so I feel pretty confident in saying it's bad...

Luckily replacements are pretty cheap. I bought a new sending unit too, just in case.

 

And hot diggity damn dog. I've got a working fuel gauge for the first time since I bought this jeep.

 

More or less. It was close enough out of the box that I didn't mess with it.