Chrysler Repair: 90 New Yorker trans problem and gas gauge problem, chrysler new yorker, variable resistor

Question
Hey,
So i have a 1990 Chrysler New Yorker 5th Avenue with the 3.3L v6. A couple
of days ago my transmission started to only go in 1st and 2nd gear and wont
go past 40mph with out revving up high. What is the problem? I can't figure it
out. Also, the gas gauge is always reading empty and i also can't figure that
out. Any help would be great. Thanks!  

Answer
Hi Craig,
The trans is in "limp-in" mode which it does when its electronic controller sense a problem which may cause damage. The fault is coded as a two-digit number in the controller memory. There is a blue 6-pin plug under the dash near the fuse box into which a diagnostic code reader (OBD-I generation) is plugged (either at a competent independent trans shop or dealer which will give you the code number and from that the possible causes/repairs can be considered. Let me know the fault code number and we'll compare notes with the manual.
On the gas gauge, the float level which operates a variable resistor in the tank has a dark blue/yellow wire that goes to the circuit board of the cluster (if it is a conventional type) or to the body computer and then as a digital signal to the electronic cluster. Let me know which type of cluster you have, and if you have a volt-ohm meter to check out the details ot either circuit. The float may have sprung a leak and so it might be falsely showing empty. By reading the resistance on that wire when the tank is full vs empty you can diagnose that as the source of the problem.
Roland