doomgaze

I've been thinking my TPS is bad for a while now, but I'm not sure if I am correct in thinking this. Here are my symptoms:<br><br>*Let up just a tad on the accelerator and the truck downshifts, then takes a while to upshift again holding a steady speed.<br><br>*When cruise is on, it surges forward. No jump in tach or speedo, but you can tell it's speeding up and then slows back down to set cruising speed<br><br>*Without cruise, no matter if I'm accelerating, or maintaining constant speed, I get a jump in the tach. It revs up about 200rpm and then goes back to normal. It never does this in the Winter, only during warmer months. And it will either do it not at all on a trip or it will rev every 5 seconds all the way down the road.<br><br>What do you think?

Smokee

The TPS sounds like a good place to start. Take it off and soak it with contact cleaner or brake cleaner.<br>Also, check your TV cable adjustment. You should have 1/8&quot; at the tranny with the accelerator at full.<br>george

doomgaze

Is there any place on the net that would give me instructions on how to take the TPS off? Or even just give pictures of the whole unit?<br><br>I looked in my Haynes manual, and from the diagram they have, I'm not even real sure which paart is the TPS.

Smokee

You can probably find info abput the TPS at: <br><br>It is the little round black unit where the throttle linkage joins the bell crank. It is held on by two 8mm screws.<br>george

jdeereboy

I sure hope the TPS is your problem as it will cost much less than what is sounds like. It sure does not sound good. Looks more like your transmission is slipping. The TPS is very easy to test with an Ohm meter. They are often replaced and pointed out as the cause of a problem but I believe they rarely fail.

David Gardner

Go to the TDR web site www.turbodieselregister.com. Then go to archives and select TPS or throttle position sensor. Should get all the info you need. I dont know if you have to be a member to access this.<br><br>Good luck hope it works out for you.

doomgaze

Update:

I originally said in the second point there was no jump in speedo or tach when cruise was on. I now notice a jump in the speedometer when I have cruise on. Sometimes it would jump several times in a row and make it all the way up to 65 when I had it set at 60.

I really don't believe it's my transmission. I had it in a year ago to replace the seals on or something on/in the transmission and the guy told me it was in excellent condition. And I do not haul anything with it.

I am under the impression that the function of the TPS is to sense what speed the truck is going. To me, everything points to the TPS. But I'm by no means a mechanic. I will have to search TDR and see if I can find more info.

Thanks for the input thus far.

doomgaze

[quote author=shrenden link=board=13;threadid=15118;start=0#142852 date=1054093981]

i had all of the same symptoms.

2 new tps's - no fix
cleaned the tps - no fix
new pcm - no fix
new trans temp sensor - you guessed it......no fix
new gov press solenoid - no fix

pulled the tps wires out of the loom - voila.....fixed.....

[/quote]

I found this on the TDR website. What exactly is &quot;pulling the wires out of the loom&quot;? What would I need to do?

Smokee

I think that the writer is saying that there was a short??? in the wiring. Who knows what wiring.<br>ANY TDR MEMBERS who can send a PM for more info?

AlpineRAM

Actually pulling the wires out of the loom does help when your problem comes from signal noise induced by other cables running parallel to the TPS cables. You can try to fix it with what I did here<br>Please look up the correct pins on your PCM before doing this, mine is a 98.5 and may be different from yours.<br><br>Good luck!<br><br>AlpineRAM

dma251

Here are my symptoms:<br><br>*Let up just a tad on the accelerator and the truck downshifts, then takes a while to upshift again holding a steady speed.<br><br>That isn't a downshift - it's your TC unlocking because it's either getting a dirty signal from the TPS or the TPS is adjusted incorrectly. I recently had the same problem, and cleaning it with contact cleaner helped for a while, but eventually I bought a new one - $150.00 from NAPA. <br><br>Try cleaning it with contact cleaner, and rotate it slightly counter-clockwise as you tighten down the bolts. If you want you can tap out the metal bushings in the two bolt holes on the TPS, and that'll give you a little more twist on it. This will give you a small margin of adjustability over when the TPS signals the ECM unlock the TC when off the throttle.<br><br>Sorry if that doesn't make any sense. Piers showed me how to do it, but this is the first time I've put it into words.<br><br>Good Luck.

olivmatt

doomgaze,

i'm the one you quoted from above. shendren.

it's probably not your tps. probably noise in the harness. you need to rewire your tps. let me know if you need help.

scott
gpcinc@yahoo.com

DF5152

sound like you ar getting alternator noise. the great brain surgens at DC ran the power wire from the alt next to the TPS wiring a simple capacitor will solve ur problem. DTT make a kit for about $35. the capacitor value should be .10 micro farads. and it gets insatlled by the computer in the TPS wiring to ground.

olivmatt

i bought the dtt capacitor black box kit........no fix.....

just get a rewire kit for the tps and eliminate the noise to solve the problem.

scott

gpcinc@yahoo.com