will7798 Posted March 21, 2016 Share Posted March 21, 2016 I found an 89 MJ in the junkyard with gauges (no tach) and pulled it to put into my 90 so I could get rid of my dummy lights. Now before I swapped it my gauge would fluctuate within a quarter tank, but now after the swap it doesn't read at all. I did notice that the plastic on the back with the copper colored lines (I'm assuming thats the circuitry) was torn where the harness towards the center plugs in. I'm not sure if that would be detrimental though because its still in contact with the harness plug. Anyone have any pointers that I might be completely overlooking? Or should I just say screw it and buy a reliable cluster off of somewhere/just carry around a jug of gas everywhere I go? Thanks. Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 21, 2016 Share Posted March 21, 2016 Yes, the copper foil is the gauge cluster "wiring" from the connectors to the gauges. If a copper trace is torn anywhere on the foil, you will have an open circuit and something is not going to work. Torn traces can be repaired by scraping the lacquer finish off the trace on both sides of the tear and soldering in a small jumper wire across the break. Also make sure the gauge mounting screws are tight as they are also make a circuit connection between the foil and the gauge posts. Try all that; if the fuel gauge still doesn't indicate you will have to replace the foil or cluster. I have plenty of HO gauge cluster foils and could send you one but they will not work on the earlier Renix clusters. Link to comment Share on other sites More sharing options...
will7798 Posted March 21, 2016 Author Share Posted March 21, 2016 Whats the difference between HO and Renix? I see it a lot and honestly have no clue what it is. Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 21, 2016 Share Posted March 21, 2016 Renix (Renault/Bendix): 86-90 MJ models, proprietary electrical system HO (Chrysler High Output): 91-92 MJ models, conforms to OBD1 standards Link to comment Share on other sites More sharing options...
will7798 Posted March 21, 2016 Author Share Posted March 21, 2016 I gotcha. And sorry if its asked a lot but all the search results I got weren't with a swap and I wanted to know if I somehow screwed up something simple Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 21, 2016 Share Posted March 21, 2016 No problem. :cheers: Link to comment Share on other sites More sharing options...
Eagle Posted March 21, 2016 Share Posted March 21, 2016 The clusters in the Renix years used a mechanical speedometer. The HO clusters (1991 and newer) used an electronic speedometer. That's the reason the clusters can't be interchanged. Worse, for some screwball reason, Chrysler not only changed the resistance range for the fuel sender, they also reversed the polarity, so if you were to ignore the speedometer and plug an HO cluster into a Renix chassis -- the fuel gauge would read backward. Back to Will7798 -- does the cluster function correctly other than the fuel gauge? If so, you should be able to bypass the printed circuit and "hotwire" the fuel gauge. All the signals coming into the cluster come through the rectangular connector that plugs into the left (as viewed from the driver's seat) side of the cluster. The fuel gauge makes contact with the printed circuit through the two screws on the back, the same ones that hold the gauge into the cluster. You should be able to get a couple of pieces of fince wire and mak jumpers to connect from the connector directly to the two posts on the back of the gauge. Do you have access to a wiring diagram to figure out which two wires to jumper? Link to comment Share on other sites More sharing options...
will7798 Posted March 21, 2016 Author Share Posted March 21, 2016 I don't have a wiring diagram no. And where the circuit is torn is on the connector closest to the speedo cable connector so idk if that would be where my problem lies if youre saying the fuel gauge is on the far left connector. Also i have the circuit foil from my cluster with dummy lights still, would that by chance be the same? Link to comment Share on other sites More sharing options...
Eagle Posted March 22, 2016 Share Posted March 22, 2016 I don't have a wiring diagram no. And where the circuit is torn is on the connector closest to the speedo cable connector so idk if that would be where my problem lies if youre saying the fuel gauge is on the far left connector. There is only one wiring connector, where all the wires plug onto the back of the cluster. If the wires are the same colors as for 1988, you should see tan wires at terminals 15 and 17 of the connector that plugs onto the back of the cluster. 15 and 17 are jumpered together -- one feeds the actual gauge, the other controls the low fuel warning light. Tap the tan wire at 15 or 17 and run a jumper directly to the positive terminal/pst on the fuel gauge, then run a jumper from the negative terminal of the gauge to any good chassis ground. That should do it. Link to comment Share on other sites More sharing options...
will7798 Posted March 22, 2016 Author Share Posted March 22, 2016 Alright thanks ill give that a shot this weekend and let yall know if it works. Really appreciate all the help Link to comment Share on other sites More sharing options...
Eagle Posted March 22, 2016 Share Posted March 22, 2016 I sit corrected. There are two connectors. The one for the gauges will be on the back of the main cluster, sort of next to the speedometer head. There is another connecter way over at the left (viewed frojm the front) side that feeds that bank of indicator lights to the left of the gauges. The main harness connector is the one you're looking for. Link to comment Share on other sites More sharing options...
will7798 Posted April 5, 2016 Author Share Posted April 5, 2016 UPDATE: sorry I forgot about this topic for a little bit, had some issues come up. So the good news is, a '90 XJ rolled into my junkyard a few days after I first posted and was able to trade the old cluster for the one in the XJ and plugged it all up in the parking lot and was good to go. bad news is later that week my fuel pump went out and left the truck stranded in the school parking lot until I could get a buddy to tow it home. Now that I have a new fuel pump in, the gauge isn't working...again. I am assuming that the floater is just stuck in the "sock hole" but either way I'm gonna take it to my buddy who is a Chrysler expert (40+ years mechanic-ing on them) and do it RIGHT, which means draining it and dropping the tank, not leaving it half full and under the truck like I did. Hopefully then it will fix my gauge for the second time. Link to comment Share on other sites More sharing options...
ComancheKid45 Posted April 5, 2016 Share Posted April 5, 2016 I believe it's the purple wire off the sending unit that is the float level wire...find where it goes into the cluster and test it for continuity ;) Link to comment Share on other sites More sharing options...
will7798 Posted April 5, 2016 Author Share Posted April 5, 2016 Will do Link to comment Share on other sites More sharing options...
DirtyComanche Posted April 5, 2016 Share Posted April 5, 2016 You really don't need to drain the tank to do the sender or pump. I doubt a dealership would even do that. You can test the sender/wiring/gauge by pulling the whole assembly out and moving the float up and down manually. Just make sure it isn't going to hang up on anything when you put it back in. Link to comment Share on other sites More sharing options...
will7798 Posted April 5, 2016 Author Share Posted April 5, 2016 I think the problem is that it did hang up when i put it in. When i redo it ill check it manually Link to comment Share on other sites More sharing options...
Megadan Posted April 5, 2016 Share Posted April 5, 2016 You really don't need to drain the tank to do the sender or pump. I doubt a dealership would even do that. You can test the sender/wiring/gauge by pulling the whole assembly out and moving the float up and down manually. Just make sure it isn't going to hang up on anything when you put it back in. You don't need to drain it, but it's a good idea to get it down to at least half a tank. Nothing like a fuel shower when you pop that o-ring and hanger loose....(yea, I made that mistake...cuz I'm smert) Link to comment Share on other sites More sharing options...
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