OldSch88L Posted September 22, 2021 Share Posted September 22, 2021 I'm currently swapping a really nice 1988 dash that I found on marketplace to replace my old cracked one. It also came with a full cluster. However, I previously swapped and made the proper mods for a 1996 full cluster with electronic speedo. The downfall was a reverse-reading gas gauge. I didn't want to deal with finding a 1991 MJ fuel sender, so I took the gauge from the Renix full cluster and did some slight mods, then installed it in the 1996 cluster. I tought some of you might want to see the differences between the two; they share the same gauge, but way different PCBs. So I guess there's more than just different senders. However, the Renix one being so simple, I'm sure one could take a 1996 cluster and convert the gas gauge to Renix duty... Link to comment Share on other sites More sharing options...
Eagle Posted September 22, 2021 Share Posted September 22, 2021 I don't understand. Are you saying that your '88 fuel gauge reads correctly in the '96 cluster, or does it read backwards? Link to comment Share on other sites More sharing options...
OldSch88L Posted September 22, 2021 Author Share Posted September 22, 2021 10 hours ago, Eagle said: I don't understand. Are you saying that your '88 fuel gauge reads correctly in the '96 cluster, or does it read backwards? The 1996 fuel gauge reads backwards in my 1988 Renix Jeep. I wanted to keep the electronic speedo so I modified and grafted the 1988 fuel gauge in the 1996 cluster. I'll test it in a feel days to see if it works. Link to comment Share on other sites More sharing options...
Eagle Posted September 22, 2021 Share Posted September 22, 2021 I haven't tried it, but I sort of figured the easy solution would be to trace the printed circuit back to the header, then pull the two wires for the fuel gauge out of the connector and reverse their positions. Link to comment Share on other sites More sharing options...
Minuit Posted September 22, 2021 Share Posted September 22, 2021 1 hour ago, Eagle said: I haven't tried it, but I sort of figured the easy solution would be to trace the printed circuit back to the header, then pull the two wires for the fuel gauge out of the connector and reverse their positions. I did a test on this a while back. Reversing wires will not make it correct in any configuration. I'll see if I can find the post later today. Link to comment Share on other sites More sharing options...
eaglescout526 Posted September 23, 2021 Share Posted September 23, 2021 I am pretty sure swapping the gauge itself may not work either. I thought the fuel gauge and the pot on the FSU were both calibrated to 0-88Ωhms? Link to comment Share on other sites More sharing options...
ghetdjc320 Posted September 23, 2021 Share Posted September 23, 2021 That makes sense. The gauge sweeps aren’t just opposite either, the ranges are different. You could use a Dakota Digital converter though. Apparently I have this problem on my 90. Someone swapped in an HO cluster and it reads backwards. But as I said it’s not like one is 0-90 and the other is 90-0. Link to comment Share on other sites More sharing options...
Eagle Posted September 23, 2021 Share Posted September 23, 2021 5 hours ago, eaglescout526 said: I am pretty sure swapping the gauge itself may not work either. I thought the fuel gauge and the pot on the FSU were both calibrated to 0-88Ωhms? Yes, on the Renix system. The Chysler system reversed the polarity AND changed the resistance, from 0-88 to something like 100-5. If my idea works, the gauge won't be completely accurate (but they never are, anyway), but my hope was that it would at least swing in the correct direction. Link to comment Share on other sites More sharing options...
OldSch88L Posted September 23, 2021 Author Share Posted September 23, 2021 To make it short, both gauges have the same contacts on the PCBs. It's just that the Renix and 1996 are printed differently. The 3 center screws line up, but the brass tabs on the renix gauge don't, and make the gauge stand out too much since the 1996 cluster case is shallower. So, the tabs also being contacts, I cut them and soldered wires and routed them to their respective places. If it works, I'll take the cluster back out to show pics of the final setup. Link to comment Share on other sites More sharing options...
OldSch88L Posted October 11, 2021 Author Share Posted October 11, 2021 Little update on the fuel gauge swap. I've put the Renix gauge in the 1996 cluster, held on by the 3 gauge screws/contacts and wired in the brass tabs correctly. The gauge worked, but the low fuel light was always on. Turns out the Renix gauge has a second, separate PCB hiding behind the tach, inside the cluster case. It's held on with 4 screws/contacts, so I took it out and grafted it in the 1996 cluster, and wiring it in. All seems fine now; I'm just waiting for the fuel to get low enough to make sure the warning light works. If it does, I might make a how-to about this whole thing. Why all this trouble you ask? I couldn't stand the jumping needle from the cable driven speedo. Also, all the full clusters I could find were the electronic ones. I already had a speed sensor from a spare transfer case, so I did the electronic speedo conversion. Then, the reverse-reading gas gauge got on my nerves; so it was either finding a 1991-1992 fuel sender, or swapping in the Renix gauge and components to go with my existing Renix sender, which I got from a Renix full cluster that came with my new dash, so there we are!!! Link to comment Share on other sites More sharing options...
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