darkside Posted May 17, 2010 Share Posted May 17, 2010 So all the gauges in my MJ quit working and am replacing them with aftermarket gauges(like autometer or sunpro) and have a question about the fuel level gauge. Now I know what wire the sending unit is but can anyone tell me the amount of resistance(ohms)the factory sending unit is. I have purchase the gauge and it is supposed to be for a chrysler/ford sending units but want to make sure I bought the right one. Thanks for any advice in advanced. Oh, also tried searching but failed to find anything. :dunno: It is an 87 MJ by the way. Link to comment Share on other sites More sharing options...
jimoshel Posted May 17, 2010 Share Posted May 17, 2010 88ohms full. 6 ohms empty. Link to comment Share on other sites More sharing options...
darkside Posted May 17, 2010 Author Share Posted May 17, 2010 Ok thanks. I guess I got the wrong one so I had the store order the correct one. The one I bought was for the chrysler/ford sending unit wich operated at 73 ohms empty and 10 ohm full where as the one that uses the GM sending unit operates at 0 ohms empty and 90 ohms full. Thanks again and hope this may help someone else out that may need this info in the future Link to comment Share on other sites More sharing options...
jimoshel Posted May 18, 2010 Share Posted May 18, 2010 If you have to, or just want to, you can use the one you got by switching the wires. The low wire from the sending unit to the Full wire on the gauge, and the full wire from the SU to the empty side of the gauge. Link to comment Share on other sites More sharing options...
Eagle Posted May 18, 2010 Share Posted May 18, 2010 Jim is correct for your '88 MJ (except that I think it's 0 ohms empty, not 6), but Chrysler changed to the opposite polarity in 1991. However, the range for the XJ/MJ was not the same as the Chrysler unit you mentioned. The Jeep unit was (IIRC) 108 to 8. But ... what the existing range is doesn't matter. You need to find out what your gauge will be calibrated for, and buy a sender that matches your gauge. Link to comment Share on other sites More sharing options...
kastein Posted May 18, 2010 Share Posted May 18, 2010 Why not fix the stock gauges? If all of them quit working at once my bet is that you can fix them all at once, easily, and you won't be tearing up your wiring and making your vehicle into a rats nest. Link to comment Share on other sites More sharing options...
darkside Posted May 18, 2010 Author Share Posted May 18, 2010 But ... what the existing range is doesn't matter. You need to find out what your gauge will be calibrated for, and buy a sender that matches your gauge. I believe the sending unit that is currently in the tank is fine so I am just getting the correct gauge that will work with the current sending unit. Link to comment Share on other sites More sharing options...
darkside Posted May 18, 2010 Author Share Posted May 18, 2010 Why not fix the stock gauges? If all of them quit working at once my bet is that you can fix them all at once, easily, and you won't be tearing up your wiring and making your vehicle into a rats nest. Well all of them didn't quit working at once, if they did I would just replace the IPC. The wiring is not going to be a rats nest. I am an automotive technician so I know what I am doing, just wasnt sure one the factory sending unit ohm range. Also the PO had already hacked the wiring and I am also fixing those mistakes. For me to get a factory IPC and correct all the mistakes and what have you it will be easier going this route. Link to comment Share on other sites More sharing options...
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