sansocal

The auto tranny in my '89 cherokee, 4.0, is acting up. It's very intermittent but heres what I observe:
- Will be driving at around 30-40 mph and truck will rev. very high with little acceleration, until around redline where it will shift very hard and put you in your seat. Then it will go into overdrive fine. Until you go back below 30 mph and go through the 30-40 mph range.
- Will not always act up when starting from a complete stop (coasting around corners sucks)
- Will sometimes rev up with very little acceleration like this from a stop, haven't tried getting it to shift like this yet.
- Removed fuse for TCM and started in 3rd or D, exact symptoms.
- Tranny shop says it shifts perfectly, and offered a $180 oil change (didn't act up when they drove it)


From what I can piece together from all this is that the truck isn't down shifting from 3rd and OD, so it just revs. until it gets in the right speed range where it shifts.

TPS is 3 months old.

sansocal

Oh yeah, this is really got me PO'd because it started happening on the way to the first day of work. (delivery driver)

cruiser54

Did you adjust that 3 month old TPS?

sansocal

Yeah i did, but it wasnt easy.. I will check that tomorrow.
Can the tv cable affect shifting like this at all?

freegdr

hows the fluid level?

cruiser54

Double check the adjustment of the TPS.

RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS 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.
IMPORTANT NOTE: Using the positive (red) lead of your ohmmeter, 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.
If you see more than 1 ohm of resistance 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.
MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body.
This manual transmission vehicle TPS provides data input to the ECU. The manual transmission
TPS has three wires in the connector and they're clearly embossed with the letters A,B, and C.
Wire "A" is positive.
Wire "B" is ground.
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. Adjust the TPS until you have achieved this percentage. If
you can't achieve the correct output voltage replace the TPS and start over.
AUTOMATIC TRANSMISSION:
RENIX automatic transmission equipped XJs 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 the
manual transmission equipped vehicles--FOR 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.
Key ON, measure voltage between "A" positive and "D" ground. 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. If you have TRANSMISSION issues check the four-wire
connector side of the TPS. If you have ENGINE issues check the three-wire connector side of
the TPS.
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.




And, have you ever adjusted the TV cable?

sansocal

The transmission shop said fluid level was fine, a little dirty (of course it is when he makes $180 to drop the pan and clean the screen)

I did have the tv cable off cause I swapped in an 87 engine, I adjusted it by pressing the button and pulling it all the way out.

I am pretty sure it's an electrical problem because if I pull the tcm fuse when it's acting up it will stop, and go into what ever gear the selector is on.

sansocal

The resistance between flat 3 wire connector wire b and the negative battery post is 83.3 ohms... I wouldnt of thought the tps would be able to work with that much resistance. So what do I just splice in another wire from wire b to the engine block?

cruiser54

That may not do it as the CTS, IAT and MAP are on the same ground circuit. Their grounds are probably high in resistance also. I have a little tutorial and diagram for you to use that will fix all of the grounds quite easily. You have no C101 connector so the resistance is most likely in the splices in the harness. Easy to find and fix.

And yes, they will run with that much resistance in the ground circuit. Did you wiggle the harness along the valve cover and over near the MAP sensor while watching the meter? On my wife's Jeep the resistance varied from 38 to 74 ohms while wiggling!!

sansocal

Thanks

cruiser54

C101 connector is the plug between the engine harness and the chassis mounted above the brake booster. Another source of bad connections and resistance.

cruiser54

Find your Intake Air Temp sensor. It's the sensor just to the rear of the throttle body, has 2 wires, and screws into the intake manifold.
Where it's connector plugs into the harness you will see that one of the wires on the harness side　is brown with a white stripe. Follow the brown with white strip wire back into the harness. You'll have to open up the split-loom plastic sheathing to follow it. It will come to a splice with 2 other brown with white wires. They're from the TPS and the CTS. The 3 wires will be　 spliced to a single wire headed toward the C101 connector.
　
Now go to the MAP sensor. Follow the brown with white wire into the harness from there. You will find a splice with 2 more brown with white wires. At the splice you will find the 3 wires connected to a single brown with white wire going toward the C101. Along with the MAP sensor that you traced, they are the ECU sensor ground port and the diagnostic connector on the passenger inner fender.
　
You now have 2 sets of 3 brown with white wires, one set on each side of the C101 connector.
　
Cut the splices out of each set of wires. You will be connecting the 2 sets of three wires together.　Solder the 2 sets of wires together and insulate them properly with tape or shrink tubing.
　
Zip-tie up your new sensor loom to allow for engine movement.　I prefer to cover it with some new split-loom or wrap it neatly with electrical tape when done.

cruiser54

I can't get my hay-okey diagram to post up. If you think you need it, PM me with your email address and I'll send it to you. If you follow the directions above, you might not need it.

sansocal

So is the wiring fix the same without c101?

sansocal

So is the wiring fix the same without c101?