Allison MD3060R throttle position sensor location

Topic: Allison MD3060R throttle position sensor location (Read 3400 times) previous topic - next topic

Allison MD3060R throttle position sensor location

May 29, 2019, 10:10:50 am

I have just returned from Steward & Stevenson Houston due to several issues. My problems started about 2 yrs ago, when I found the dip stick plug(drivers side) missing and the fluid level about 3 gals. low. I changed fluid and filters immediately. About 1 yr. ago I went to Steward & Stevenson Longview, TX. They changed fluid and filters and set adaptive shift and hit the back pocket. No help and no changes. Steward & Stevenson Houston worked on it for 6 hrs. and changed the Speed Sensor(old one was aftermarket), checked pressures(all good 190psi). The computer stuff was sent to Allison Tech Center twice. I don't know what changes if any was done with electronics and the bill says nothing about it. They did say that the throttle position sensor was only showing 25% when throttle was WOT. They have no knowledge of CAT 3116 and that sensor.

Where is the throttle position sensor on my '95 U-240 with a CAT 3116 and Allison MD3060R?? What does it look like?

Re: Allison MD3060R throttle position sensor location

Reply #1 – May 29, 2019, 10:23:36 am

Quote from: pthurman48 – May 29, 2019, 10:10:50 am

Where is the throttle position sensor on my '95 U-240 with a CAT 3116 and Allison MD3060R?? What does it look like?

No idea if my coach (C8.3 with MD3060 - no retarder) is the same as yours, but for what it is worth...

My throttle cable bracket (on the injection pump) has two control cables attached. One cable goes to the Bendix air throttle/cruise control unit. The other cable goes to the throttle position sensor, which is mounted on the frame rail, passenger side, hidden behind a hydraulic reservoir.

I think it is just a type of variable resistance transducer that converts mechanical movement into a electrical signal.

It is possible that the control cable is not firmly attached at the throttle bracket, and is not moving correctly when your throttle lever moves.

Photo below:

Re: Allison MD3060R throttle position sensor location

Reply #2 – May 29, 2019, 10:25:31 am

Yup, open the bed and look for the second (first is throttle cable) cable coming from the injection pump (passenger's side of engine).

May be able to see it from the back as well, can't remember.

Re: Allison MD3060R throttle position sensor location

Reply #3 – May 29, 2019, 12:26:10 pm

Thanks for the quick reply. Mine is just like yours and in the same place. Now does anyone have a part number or where to buy it, except FOT

Re: Allison MD3060R throttle position sensor location

Reply #4 – May 29, 2019, 12:29:04 pm

Suspect (never shopped for one, so don't know) that this is an Allison part.

Have you diagnosed it as bad-- electrically? mechanically? Said another way, what is wrong with it?

Re: Allison MD3060R throttle position sensor location

Reply #5 – May 29, 2019, 12:38:12 pm

Steward & Stevenson Houston did say that the throttle position sensor was only showing 25% when throttle was WOT. They have no knowledge of CAT 3116 and that sensor.

Re: Allison MD3060R throttle position sensor location

Reply #6 – May 29, 2019, 12:45:37 pm

Pat,

It may be as simple as a cable adjustment. If may be a bad electrical connection, or, yes, it could be a bad TPS.

I am quite surprised that a S and S Allison dealer could not diagnose this-- no different than any other mechanical engine paired with that transmission.

Re: Allison MD3060R throttle position sensor location

Reply #7 – May 29, 2019, 12:50:15 pm

You might try adjusting to better correlate to the pedal position. There should be a slotted plate that can be rotated to improve the TPS value with the pedal value.
If not , it is set VIA computer correction. Many vehicles have both options. The mechanical option being easier of course and should be done with replacement.
It should be some type of voltage reader. Typically a 5 v in to a signal value of a percent of 5V.
It has to have a ground someplace also and history shows , look there first.
IE verify good ground, then find the input voltage value and then the signal value.

Re: Allison MD3060R throttle position sensor location

Reply #8 – May 29, 2019, 01:18:25 pm

Adjusting a TPS

This subject came up in a recent thread, and I posted the reference linked below. A bit over my head - might require professional help.

Re: Allison MD3060R throttle position sensor location

Reply #9 – May 29, 2019, 02:12:45 pm

This is a picture of the stuff on the injector pump. Engine is NOT running. Cable on the left is the cable coming from the Bendix Cruise Control Panel. It is also the throttle pedal. Cable on the right goes down to the TPS on the passenger side frame rail like chuck's. Notice on the TPS cable that the setup allows a lot of movement in the throttle before the sensor gets any movement of the cable. You can see this not dirt on one part of the cable end.

Re: Allison MD3060R throttle position sensor location

Reply #10 – May 29, 2019, 02:33:24 pm

Thanks chuck for that pdf. your are right that is the adjustment procedure. My cables and sensor all look like nothing has changed in yrs.

Re: Allison MD3060R throttle position sensor location

Reply #11 – May 29, 2019, 02:38:47 pm

Look through the setup info above. My guess is that that little slop is designed in and needs to be there.
## The retaining screws on the cable shroud have slots for the adjustment .
Depending on symptoms, IE very early upshift at WOT, reduce the cable slack at those screws/ move the shroud/ until it acts better.
I doubt that any big mistake can be made , adjusting inside of the factory ranges. IMHO.
What are the faults? no shift, early shift , late shift?

In my case I loosened my adjustment for earlier upshift.

Re: Allison MD3060R throttle position sensor location

Reply #12 – May 29, 2019, 02:39:33 pm

I am still shocked that S&S in Houston did not know how to adjust this common TPS. Probably worth a call to their Allison shop foreman.

Re: Allison MD3060R throttle position sensor location

Reply #13 – May 29, 2019, 04:02:27 pm

This may or may not be the correct TPS if you want to replace it: Part no 29507766 enter at TKT Sales Allison Transmission Parts Supplier: Part Number Search

Your TPS should have a part number on it for more assurity.

TKT sales is a good place to buy these type parts.

Re: Allison MD3060R throttle position sensor location

Reply #14 – May 29, 2019, 04:07:01 pm

I previously had a 94 Bluebird BMC with Cummins 8.3 and Allison MD3060.
Threads that may help:
TPS to throttle bracket, and tps - Wanderlodge Owners Group
TPS surprise ( throttle position sensor ) - Wanderlodge Owners Group

Re: Allison MD3060R throttle position sensor location

Reply #15 – May 30, 2019, 07:37:36 pm

Just a little update: I have spent all day trying to find a TPS (29516192) and have found out that is not a TPS number, it is an assembly number that is obsolete. So now I think my TPS number is a 29509928 and this is the TPS number not an assembly number. The assembly number also included a bracket and stuff. This part is not easy to find, must be ordered from the factory?? After all this it is only about $400.00 and will take a week or so to get here.

Re: Allison MD3060R throttle position sensor location

Reply #16 – May 30, 2019, 07:43:48 pm

Pat,

Have you VERIFIED that the TPS is defective and not just out of adjustment or bad connection?

Re: Allison MD3060R throttle position sensor location

Reply #17 – May 30, 2019, 07:57:13 pm

No way to check other than with Alison test equip. S&S Houston said it only show 25% at WOT. The adjustment or bad connection is not a problem. I have checked with ohm meter : outside terminals(hot and ground) 12.92k ohm, ground to signal at rest 8k ohm, ground to signal at full extent 13.25k ohm and slowly returns to about 8k ohm in about 15 seconds.

Re: Allison MD3060R throttle position sensor location

Reply #18 – May 31, 2019, 10:41:20 am

Don't know if its possible to disassemble the device which is essentially a lineal potentiometer, but if so I'd try gently cleaning the resistive strip and sliding contacts with some Deoxit D5.

Re: Allison MD3060R throttle position sensor location

Reply #19 – May 31, 2019, 10:54:20 am

Quote from: pthurman48 – May 30, 2019, 07:57:13 pm

No way to check other than with Alison test equip. S&S Houston said it only show 25% at WOT. The adjustment or bad connection is not a problem. I have checked with ohm meter : outside terminals(hot and ground) 12.92k ohm, ground to signal at rest 8k ohm, ground to signal at full extent 13.25k ohm and slowly returns to about 8k ohm in about 15 seconds.

Sounds faulty from here.

Re: Allison MD3060R throttle position sensor location

Reply #20 – May 31, 2019, 12:23:42 pm

Better to replace the TPS and be done with it.

Not a clean area to work in and not a easy area to work in. One and done with new TPS.

Re: Allison MD3060R throttle position sensor location

Reply #21 – June 01, 2019, 08:27:41 am

Is there a temporary "work around" for a failed TPS? Can the coach be driven without it or is this a "side of the road event"?
What are the symptoms of a failing TPS? I have no experience with one and would like to be a little prepared................

Re: Allison MD3060R throttle position sensor location

Reply #22 – June 02, 2019, 06:21:55 pm

I have had some of these same thoughts Fourtravelers. So I unplugged the TPS and drove down the road. From the way it shifted both up and down, the signal to the tranny was a WOT. The tranny would not shift up until WOT and 2600 RPM( normal shift point) and it would down shift higher speeds that normal decelerate. The only bad thing about it was that the 5-6 shift was really bad with engine run away(500 rpm). You cannot make it up shift unless you reach WOT and 2600 RPM.

I then plugged in the old TPS and drove. The up shifts were all good at WOT and 2000 RPM(should have been at 2600 RPM). The shift from 4-5 is bad with the same engine run away(500 RPM). NO down shifts at all. Like this I can use the shift pad and control the tranny OK, but you have to pay attention, both on the up shift and the down shift.

Re: Allison MD3060R throttle position sensor location

Reply #23 – June 17, 2019, 10:30:34 am

Dan you had it right. Good news on TPS(29509928) made a big difference in all shifting both up and down. I installed the new one in the old position, probably needs some adjustment. New TPS(29509928) was $388+shipping=$404.

Affiliate Notice