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87 Renix TPS issues

WAD357

NAXJA Forum User
Location
Eastern LI, NY
My brothers 87 cheif has been having an issue with the TPS..

He just replaced it as it was idling weird and starting to run rough. I had set it to proper spec 0.8 volts and drove it briefly around the block and it ran great for a minute and went right back to what it was doing. I then checked supply power to find about 4.0 volts where it is said you want 5.0. grounded the meter to something else and got 5.0 volts. So i figure it to be the ground, and then jumped the ground out to my own. It not runs worse and will not shift? Any help is appreciated thanks
 
Here's a paraphrased version that I keep on hand for just such occasions:

For an 87-90 4.0:

Test is done with throttle closed, connectors connected, ignition on, engine off. Insert probes through back of connectors to make readings. Use a high impedance meter. Adjust TPS by loosening mounting screws and turning in mount.

For manual connect + probe to terminal A, and - to B. Take a reading, which should be in vicinity of 5 volts but probably lower. Note the reading well. Now move the positive probe to terminal C. The reading should be 16 percent of the previous reading.

For Automatic, use the square, 4-terminal plug. Connect probe + to terminal A, and - to D. Note reading, which should be in vicinity of 5 volts. Now move probe + to terminal B. This reading should be 82 % of the first.

Note: later versions of this procedure say to disconnect the plug to get the ~5 volt reference voltage. Replug then use the reference voltage to set output voltage.
 
Matthew: You can also test the auto trans TPS on the engine side of the TPS using the manual trans instructions. This prevents a wild goose chase as the trans side may test/adjust just fine but the engine side of the TPS can still be faulty. I put together some instructions outlining the procedure if anyone is interested. PM me your email address with a note saying "TPS" and I'll send them to you.
 
Matthew: You can also test the auto trans TPS on the engine side of the TPS using the manual trans instructions. This prevents a wild goose chase as the trans side may test/adjust just fine but the engine side of the TPS can still be faulty. I put together some instructions outlining the procedure if anyone is interested. PM me your email address with a note saying "TPS" and I'll send them to you.
It's a good point that you should always test both parts even if you end up using the trans side adjustment. I don't think I'll need those instructions, since it's been over ten years since I last owned a Renix rig, but appreciate the offer.
 
It's unfortunate that most instructons for testing the TPS on auto trans equipped Renix Jeeps have you testing only the trans side even when trying to diagnose a driveability problem. I've seen TPSs bad on one side and good on the other side.
 
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