Engine/Transmission (1994 - 1998) transmission problem?

[Godzilla1]

I just purchased a 95 3500 2 whl drive auto, transmision has about 4k miles on it, the truck shifts in and out of od, any suggestions to what might be the problem?

 

[copp]

This is one of the few questions i can answer from experience . You probably have a dirty or bad TPS (throttle position sensor) switch. Its an expensive little switch but most often is the culprit. I just replaced mine on Monday of this week and for the first time in a month my truck isn't kicking out of overdrive any more . The TPS switch should read on a scanner at idle 1. 0 volt(+- . 2volts) At wide open throttle the output voltage must be 2. 2-2. 9volts higher than at idle speed. Mine read 1. 0 at open throttle so my truck would get the signal from the PCM to downshift for a second and then try again. Hope this is it . Good Luck



shorty

 

[Godzilla1]

just returned from a camping trip, is there a way to fix the tps , or do i have to go out and buy a new one, i thought i saw somewhere that this could be repaired

 

[copp]

zainman as far as i can tell by looking at my old switch its a sealed unit I guess it wouldnt hurt to take it off and check the contact wires and look it over . Mine had alot of dust and rusty colored powder in the middle opening . It only takes a few minutes to remove it Maybe you could save yourself $150 bucks but keep in mind that 95's were known for having bad TPS switches.



shorty

 

[Dfuruness]

I had the same problem and I had to replace the TPS with a new one.



Donny Boy

 

[Joe G.]

zainman,



Hose it down with contact cleaner around the shaft. Then work the linkage back and forth. Repeat a few times. That may help. I had my TPS replaced when the truck had 37K on it. Big arguement with dealer, but they replaced it under warranty. That TPS is still working. Every oil change I try to drown it with contact cleaner. So far, so good. 192K miles on the truck now.

 

[illflem]

My tps was acting up at 20k, used the same system Joe describes and have continued at every oil change. 178k on the same stock tps with no more problems. No need to remove the tps to do this.

 

[Godzilla1]

thanks for the replies, i ordered a new tps and will be installing it this weekend, man that is one pricey son of a gun, the local 5 star quoted me @ $200. 00, he said he would give me a break and charge me $ 180. 00 and i said no thanks, i purchased it through my brothers company for $100. 00. thank you very much

 

[shendren]

man... ... don't get me started on tps's!!



i have just spent the last 2 mo. chasing down the same frappin problem... . i drowned mine in cleaner..... as a matter of fact, i drowned several new ones in cleaner.....



pulled the 3 silly wires out of the wire harness back about 2 feet..... and the thing quit acting up... . in the 2 mo. i chased down many many suggestions..... be careful. check your voltages. pull the wires out of the harness. i think it is noise. i don't think they just go bad as some might think.



i changed mine when i bought it with 50k mi. as it was doing the same thing as yours 6 mo. ago. then voila, it all started back up again. bill kondolay suggested it was electrical noise early on... ...

 

[Taz]

Were exactly is the TPS sensor?

 

[Godzilla1]

when you say noise, do you mean interference from other wires that are in the harness?

 

[Godzilla1]

ok , I replaced the TPS on Sat. morning, worked fine for about 75 miles now it's doing the same thing it did before I changed it, any info would be great

 

[shendren]

TPS = throttle position sensor... .

 

[shendren]

yes, when i say noise. i mean with other wires in the harness. pull it out and you will be fine. it's probably not your tps... .



now aren't you glad you dropped $150 on that new tps!! keep the old one.

 

[Godzilla1]

I just returned home from work and started to pull the three wires from the harness, do I take them completely out as far back as I can? It's getting dark now so I will have to finish tomorrow. Any more info would be great.

 

[shendren]

i just pulled mine back about 2-3 feet, ran black tape and wire loom around them. stopped my problem cold. not to say that spraying the tps and cleaning and all that other crap won't help. it didn't help mine... . the tps was jumping from the electrical noise in the harness i suppose... .



good luck.

scott.

 

[Godzilla1]

I just read in another post that the TPS has to be adjusted. How is this done?

 

[shendren]

TPS Adjustment

The throttle position sensor, shift lever, and throttle valve cable are critical to proper operation of the transmission. If one or more of these are out of adjustment or if the TPS is noisy, shifting will be erratic. Before performing any adjustments, check the transmission fluid level and sniff the fluid. Do not make any adjustments until the fluid level is correct, and burned fluid has been replaced.

The service manual says to adjust for 0. 8-1. 2V at idle. On many trucks, this voltage is too low, resulting in TCC chatter at moderate throttle loads. The TPS is not officially adjustable but the mounting holes are slotted and the body can be rotated slightly. Adjustment is relatively easy, and requires only a digital voltmeter and a few hand tools. A little adjustment goes a long way...

TPS wire color code:

• Black = ground

• Orange/dark blue stripe (center pin) = signal

• Purple/white stripe = 5V power

Testing and adjusting the TPS:

1. With the key "OFF", unplug the connector from the TPS.

2. Turn the key "on" and insert DVM probes into the connector to reach the connector pins. Short pieces of wire or paper clips can be used to extend the DVM probes for reaching into the connectors.

3. Read from the purple wire to the black wire (these should be the outside pins). Power should be 5V with the key "on".

4. Turn the key "off" and plug the connector back onto the TPS

5. Insert the leads from the digital volt meter into the back of the TPS connector. The DVM negative probe goes into the back of the connector cavity with the black wire. The positive DVM probe goes into the back of the connector cavity with the orange signal wire.

NOTE: Push the probes into the rear of the connector until the probe tips reach the metal connector pins.

6. Loosen the TPS mounting screws

7. With the engine off and key on: Adjust the TPS position for 1. 2 to 1. 5V on the signal wire with the throttle at the idle position - more voltage makes more TC clutch pressure, too much will set a fault code. Often, adjusting for 1. 4 to 1. 5V at idle will cure TC clutch chatter under light load conditions. NOTE: The factory setting is 1. 2V max, so proceed carefully.

8. Tighten the TPS screws, slowly open the throttle to the WOT position and then return return to idle. Watch for voltage jumps - the voltage should change smoothly from the idle value to at least 3. 5V at WOT (5 volts is all you should be able to get). If the sensor voltage jumps or drops unexpectedly - replace the sensor

 

[Godzilla1]

shendren, thank you very much for the info, this problem seems so minor, but man is it annoying, i hope to get to after this weekend

thanks again,

this is the best $35. 00 i have spent in a long time