1983 CJ-5 gauge electrical problems

1983 CJ-5 gauge electrical problems

cdlongjr

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Newark, De
Vehicle(s)
1983 Jeep CJ-5, 1987 Wrangler YJ, 1974 J-10
Finally got around to checking the fuel & water temp gauges that aren't working. If you rmember, both gauges peg to the right when the keyy is turned on. After using the trouble shooting guides that Brook suggested, I found that the I terminal wasn't hot, (use is good), I ran a jumper to the I terminal from the cigarette lighter. I was steady hot & when I checked A terminal, it too was steady, bright hot. Now the fuel gauge was pegged to the left, & I know there's gas in the tank. When I checked S terminal, it was steady, bright hot. Thinking the PO may have switched the wires on I & S terminals, I reversed them. No difference in the gauges. I placed the red wire back on S terminal & the pink wire back on I terminal. Now, all 5 terminals on the gauges are steady, bright hot.
I just rechecked all 5 terminals, with the jumper to the lighter disconnected, & all 5 are steady hot. The I terminal isn't as bright as the other 4.
Did I screw up? What should I do next? Momma is going to be driving the 5 for awhile, & I need to make sure the 5 is tip top. All I need is an "I'm out of gas or this thing's overheated problem.
 
When I disconnect the red wire from the S terminal, all 4 other terminals are not hot.
 
I also ran a ground wire from the battery to the speedo, no difference. I have removed, cleaned & reinstalled the ground wire @ the gas tank. Both gauges still peg to the right.

Anyone tell me where the tube to frame ground is located? I've looked for a braided strap, but can't find anything.
 
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CD, I think you need to do some basic trouble shooting of the gauges with an OHM meter.

The fuel and temp gauge work by one side being hot all the time and the other terminal will go to a variable resistance to ground. The sending unit (fuel and temp) change resistance and that controls the gauge.

You need to use an OHM meter to ground on the sending unit wires to test them and also need one to test the gauges. Here is a great guide for checking the gauges.

Just blindly hoking up wires to hot or ground may have fried something... :)

attachment.php



To test the sending units, check the resistance to ground and write it down. Then fill the tank and warm the engine. There should be a marked change in resistance for both. I can look up what they should read (compared to the cart) cold / hot and empty / full when I get home... :)
 
Ok CJ.
I used the gauge site this morning w/ a test light. I'll go get a multimeter & see what happens.
 
Longhorn.

I'm glad you posted that site as I didn't know John had his gauge info on team rush's site now.
 
Ok, got a multimeter. The meter was set on OHMS 2K & I used the cigarette lighter ground for the 1st three. The strap was still hooked up between the 2 gauges. Speedo is still in the dash. I have removed, wire brushed, (wire end & mounting point), cleaned & painted every ground wire that I could find.
Grd to S 71 I was .126
Grd to I 51 I was .107
Grd to A 51 I was .109

S to I 21 I was .024
S to A 21 I was .021
I to A 0 I was 0

Now what?
 
I'll give you a little advice, something I learned over the years of messin around with Jeeps and electrical systems. I hope you will take this advice to heart. If I ever get drunk, or crazy enough to offer you any advice regarding electrical problems, IGNORE ME. I have no clue, and you would most certainly eather burn your Jeep to the dirt, or be hopelessly stranded on the side of the road somewhere. Good luck !
 
CW has got a point for sure. I would check the senders with the meter & see if they are in range.
 
CW has got a point for sure. I would check the senders with the meter & see if they are in range.
Temp. gauge calibration:
C (cold)........................ 130 degrees--73 ohms
Beginning of band.......... 171 degrees--36 ohms
Top of band.................. 242 degrees--13 ohms
H (hot).......................... 270 degrees---9 ohms
Fuel gauge calibration:
Empty--73 ohms
Half-- 23 ohms
Full--10 ohms
 
Temp. gauge calibration:
C (cold)........................ 130 degrees--73 ohms
Beginning of band.......... 171 degrees--36 ohms
Top of band.................. 242 degrees--13 ohms
H (hot).......................... 270 degrees---9 ohms
Fuel gauge calibration:
Empty--73 ohms
Half-- 23 ohms
Full--10 ohms
Its going to be hard to accurately duplicate these temperatures and values so if you close and there are no "over range" meaning "open connection" then the sensor is probably OK. My temperature meter heated up faster than the CJ's temperature sensor so there is a kind of lag in the readings. About a 100:1 difference in mass. The actual resistance vs. Gauge display is as follows:

Temp. gauge calibration:
C (cold)........................ 130 degrees--73 ohms
beginning of band.......... 171 degrees--36 ohms
Top of band.................. 242 degrees--13 ohms
H (hot).......................... 270 degrees---9 ohms
 
Ok, remember, I ain't much count w/ this meter, so please help me out by telling me how to test this stuff. I'll check the sending units this morning. I will put the meter between the gauge & wire to sender, then get the readings.
Isn't there a problem w/ the high readings when the terminals were tested to ground, as the readings were twice as high as they were supposed to be?
Is there a way to test the ground from the fuel level sending unit to the frame?
 
When key is turned on, fuel pegs right, temp stays left. With temp sender disconnected, fuel gauge pegs right, but goes slower.
Reversed test light on temp sender, Hooked the clip to the + terminal, sender has good ground.
Engine is cold, can't get steady ohm reading @ sender. Starts to read then goes OL, (no resistance). Got 2 steady readings @ the gauge, .545, then .539, (these were after several tries, seems the plug ends don't want to make good contact). Then I tried straight into the wire, same problem. Most tries would start to read, then go to OL, (no resistance). Used a jumper to check the factory wire, wire has .001 ohms.
Ohms betwen gauge & fuel level sending unit wire are .906. With the ground disconnected @ the fuel tank, the fuel gauge still pegs right. I have 10 volts @ the fuel tank ground & .008 ohms.
 
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I'm sorry I'm not much help in these matters.:( I'm more of a wrench turner,fabricator than a electrician. Like Cold Water was telling you Jeep electrical systems are mysterious beasts. I converted mine over to Auto Meter 2 5/8's Liquid filled mechanical gauges. :rolleyes:
 
I have to say I will not be any help either. I chased my fuel gauge with John Starks notes and never could make it work even after buying a new jeep gas gauge.(my temp never worked since I got the jeep it already had a autometer)
My answer was the same as longhorns, new autometer gauge and now everything works great.
 
I have emailed John, (the guy that wrote the gauge page). Hopefully someone here or John will help me get them working again. I feel the gauges need replaced, but I won't spend the money until a knowledgable person tells me that. I want her original. Just like the 1964 IHC-ALF fire engine I'm trying to restore. You ought to go thru the problems finding help/parts for her!
 

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