blazer 2008

I thought my TPS was going,eratic shifting at 30 mph,not harsh just mild.TBS didn,t test right so bought new one and I can only get 4.8 volts on the input test.It doesn,t matter how I move the TPS the volts stay the same.I,m not getting a good reading on the output,it shows neg. 1.4, maybe bad connection,just using paper clips inside harness.It still runs but wants to make up it,s mind on what gear to be in at 30mph.It is a 1989 4.0, auto tranny cherokee.I,ve done the other stuff like new grounds etc.

freegdr

Just a thought have you adjusted the detent cable ever it also controls tranny pressure for shifting ?

cruiser54

Read this:



RENIX TPS ADJUSTMENT

Before attempting to adjust your TPS, there are two things that need to be done.

1) Be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.

2) With the Key OFF, and using the positive (red) lead of your ohmmeter, set on the lowest scale, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.

TPS ADJUSTMENT FOR ENGINE ISSUES

Both RENIX manual and automatic transmission equipped XJs and MJs have a flat three-wire connector to the TPS which provides data input to the ECU. The three wires in the connector are clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. DO NOT UNPLUG THE CONNECTORS !! Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you
have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over.

Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage.

TPS ADJUSTMENT FOR AUTOMATIC TRANSMISSION ISSUES

RENIX automatic transmission equipped XJs and MJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as outlined above—FOR ALL ENGINE MANAGEMENT RELATED ISSUES.

However, the automatic TPS also has a square four-wire connector, clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. First off, DO NOT UNPLUG THE CONNECTORS !! Key ON, measure voltage between "A" positive and "D" ground by back-probing the connector. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.

For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced. The square 4 wire connector is just not used.
Revised 12-15-2013

Also do this just because:
Cruiser’s Trans Plug Refreshing


Over near the transmission dipstick tube are 2 rather large connectors. One is black and the other gray. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and transmission solenoids.
Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.


Additionally, if your Jeep is an 87 to 90 Renix, it’s always a good idea to reach up under the glovebox area and unplug the connector to the TCU and spray it out along with the receptacle of the TCU. While you’re there, find the fuse right in that area for the TCU. Remove it and spray out it’s receptacle and clean any corrosion from the fuse.

Revised 9-10-2012

blazer 2008

I read on one article that my input should be 5 volts and output should be 4.2 and then devide the two and should have a .830 number

cruiser54

Forget all that crap.

Post 3 has the correct way to test a TPS.

BUT, you need to do the other tips FIRST.

blazer 2008

I did the ohms test and nothing,I kicked and bent everything and if I had a dog I would yell at him.I did a quick test on my input and I get a 4.08 reading all the time,haven,t tryed output yet,I,m mad now so is beer time.Can you fly here ?

cruiser54

There's no ohms test for a TPS. I don't fly.

Jeepcrazy5722

Could we clone you then? A Cruiser clone would be a nice addition to my tool box.

cruiser54

I don't speak Canuckian....

Besides, my Tips are sooo easy......

salad

Sure there is. There're just no published min & max values. It's very simple to check for flat, open, and dead spots with a multimeter in resistance mode.

It's real easy. We pronounce "Prescott" like it's spelled

cruiser54

Preskitt, like biscuit...........

blazer 2008

I meant the ohms test for bad ground you had suggested.I didn,t find anything wrong,but I only get a 4.08 input reading.So do I just do my math and set up my output now ?

cruiser54

Do post #3 first to every connector you can see in the engine bay.
Then, do the TPS adjustment on the "engine" side of the TPS per my instructions.

blazer 2008

OK ,thanks will plug away at it again,sorry for my ignorance,this my first computer vechicle,all my other stuff are carbed,nice and easy to work on

cruiser54

Not ignorance at all.

You just got a batch of not-so-clear info. Keep us posted.