Speedo Wiring Please HELP

[tonkatrucksryan]

I just finished wiring everything. Thank you all for the help!!!! I am having major issues w my fuel gauge. I don't trust what the other PO did. They brought it here 3 mo ago with less than a quarter of a tank. I have driven it anywhere it isn't registered, I have had it running a lot though. When I finished up wiring it and started it and the fuel gauge read full. I don't know if the positive wire is on the right terminal I have switched. PLEASE let me know if you have a wiring diagram for a speedo for a 75cj.

 

[7D8CJ]

I just finished wiring everything. Thank you all for the help!!!! I am having major issues w my fuel gauge. I don't trust what the other PO did. They brought it here 3 mo ago with less than a quarter of a tank. I have driven it anywhere it isn't registered, I have had it running a lot though. When I finished up wiring it and started it and the fuel gauge read full. I don't know if the positive wire is on the right terminal I have switched. PLEASE let me know if you have a wiring diagram for a speedo for a 75cj.

Ck out this link ... http://www.painlesswiring.com/Manuals/10106.pdf

 

[tonkatrucksryan]

I am having issues reading this. You sent this to me before. The speed has the temp and fuel in it when I bought it new it has a jumper between the two gauges. The temp has only one spot for a wire and the fuel has two spots one being pink and an orange ish color wire The temp has a purple and white. I think the they might be messed up and they don't match the painless wiring diagram


HELP

 

[Old Dog]

Did you check out the gauge info in the first post of this thread.
http://www.jeep-cj.com/forums/f99/useful-info-thought-id-share-665/

 

[tonkatrucksryan]

Yes but my wires are different colors and I don't know why

 

[defibvt]

Probably because they used whatever wire they had. You are going to have to trace wires in order to see if it is correct.

 

[7D8CJ]

I am having issues reading this. You sent this to me before. The speed has the temp and fuel in it when I bought it new it has a jumper between the two gauges. The temp has only one spot for a wire and the fuel has two spots one being pink and an orange ish color wire The temp has a purple and white. I think the they might be messed up and they don't match the painless wiring diagram


HELP

I used the painless wiring in my 78 cj. probably the same as yours. The speedo is aftermarket. Hope you can see the colors. Remember to add a good ground at a speedo stud. Hope this helps.

 

[tonkatrucksryan]

My speedo is dif than yours I have three studs on the right (fuel) Pink,light orange and the jumper. on the left (temp) I have the jumper and purple. Ours are really close. Thank you I will try more on Sunday

 

[billyocup]

My speedo is dif than yours I have three studs on the right (fuel) Pink,light orange and the jumper. on the left (temp) I have the jumper and purple.

Tonka - Can you post a pic of the back of your speedo? I've been looking at the stock speedo that came out of my 75 and it's wired the same as 7D8CJ's, with 2 studs on the fuel gauge and 2 on the temp. Looking at the wiring legends from the FSM and my Painless harness, the pink wire comes from the fuel sending unit and should go to the S terminal on the fuel gauge (left side if you are looking at the back). The orange wire goes to the I (or right) terminal on the fuel gauge and then is jumpered to the I terminal on the temp gauge. The purple wire comes from the temp sender at the engine and goes to the S terminal on the temp gauge. From what I can tell, the stock harness and the Painless harness are color coded the same.

I haven't hooked any of my stuff up yet, so I have no idea if this works or not , but that's what I see from the diagrams I have. Sure would like to know what the 3rd terminal on your fuel gauge is (ground??).

Post a pic if you can.

Good Luck - Bill

 

[billyocup]

Tonka - I've been studying the wiring diagram in the FSM a bit more and it appears that there is supposed to be a 3rd terminal on the stock 75 fuel gauge. It's marked A on the diagram. That should be the jumper to the temp gauge. The terminal marked I, shows a red wire coming in from the fuse block and then jumpers over to the oil pressure gauge. The I terminal on the fuel gauge is marked "constant voltage regulator" and I'm assuming the red wire coming in is the power from the fuse block.

The Painless harness has 4 wires grouped together for the fuel and temp gauges. Pink, Red, Purple and Black. In the instructions I have for the Painless harness, it says to connect the pink wire to the fuel gauge post nearest the glove box (S) and the red wire to the remaining post. The purple goes to the temp gauge and the black to ground on a speedo cluster mounting bolt. Based on what I'm seeing on the factory diagram, I would attach the red wire to the right hand terminal on the fuel gauge that doesn't have the jumper to the temp gauge.

The only thing I can think of is that the "after market" combined the I and A terminals on the fuel gauge at some point and that my speedo isn't a stock unit.

Anyway, I hope that helps. Bill

 

[bondo258]

Just a reminder, running the gauge cluster even briefly without a ground path, will burn out the fuel gauge sender. It gets 12 v unreg, instead of the regulated current.

 

[tonkatrucksryan]

I already have the speedo installed and the dash bolted back in. I put four gallons of gas in it out of a can this weekend and it went up a bit. I just don't know how large or should I say small my tank is. I will check when I get home if I have a pic of the old one. Thank you

 

[TeamRush]

This might help...

Take the 'Pink' wire off the terminal, check it for resistance.
10 Ohms Full, 90 Ohms empty.

If your gauge sender isn't getting a good electrical 'Ground' (and most don't) the resistance will be MUCH higher making your gauge read wrong.

Most people don't know it, but there are also dials to 'Zero' your gauge for 'Full' and 'Empty', but the sender has to be working correctly for that to happen...

So test your 'Pink' wire, see if it's within the specified range,
And if so, then you might have a close look at your gauges.

 

[Niedhogg]

Just a reminder, running the gauge cluster even briefly without a ground path, will burn out the fuel gauge sender. It gets 12 v unreg, instead of the regulated current.

This might help...

Take the 'Pink' wire off the terminal, check it for resistance.
10 Ohms Full, 90 Ohms empty.

If your gauge sender isn't getting a good electrical 'Ground' (and most don't) the resistance will be MUCH higher making your gauge read wrong.

Most people don't know it, but there are also dials to 'Zero' your gauge for 'Full' and 'Empty', but the sender has to be working correctly for that to happen...

So test your 'Pink' wire, see if it's within the specified range,
And if so, then you might have a close look at your gauges.

Can just the fuel gauge be purchased, if in fact the guage has been ruined in some way??

 

[TeamRush]

You can buy just the gauges, but the replacements aren't often factory quality, and most are not adjustable.

Without testing the sender for resistance (Ohms) you won't know if it's the sender, or the gauge.
Testing the Pink wire will tell you if the sender is doing it's job or not...
Then you will have a solid place to start.

 

[Niedhogg]

You can buy just the gauges, but the replacements aren't often factory quality, and most are not adjustable.

Without testing the sender for resistance (Ohms) you won't know if it's the sender, or the gauge.
Testing the Pink wire will tell you if the sender is doing it's job or not...
Then you will have a solid place to start.

Ok, I'll run the tests..