1998 Freightliner FS-65 Throttle Position Sensor

[FawnaFox]

My 98 FS-65 has random instances where the throttle stops responding. I know that it’s the TPS (throttle position sensor) and I need a new one. What part do I need? All I know is that the throttle pedal is made by Williams Controlls.

 

[ewo1]

How do you know its the sensor and not the wiring? How did you check it?
What motor is in your bus?

 

[FawnaFox]

How do you know its the sensor and not the wiring? How did you check it?
What motor is in your bus?

The wiring harness is free of corrosion, my bus has a 5.9 Cummins ISB, 24 valve. The bus has had problems before.

 

[ewo1]

ok, but, you still didn't explain how you checked it. this is important.

Post 317 of the thread had the diagnostic testing procedure for a aps/ivs circuit. Yes this is for international but the sensors are all just about the same. I will try to verify if Freightliner is different but for now, look t your voltages. Losing the 12v to the sensor is very common.

I go to go out now but when I get back I will try to verify more.

post #17

Slow/dead pedal at startup

So I got an interesting issue going on my 2nd bus, which I call the milkshake bus. It's a 2006 Amtran RE, DT466e/md3060. I did an in-frame on it last year and successfully drove the bus from Miami to Central Texas, pulling a toad, with no issues whatsoever. 65-70 MPH all the way! When I got...

www.skoolie.net

Throttle Position Sensor Fits 2001-2007 Freightliner FS65 Dorman 738LG32 | eBay

Throttle Position Sensor. Throttle Sensor Service Kit. 2022 DT Auto Parts Inc.

www.ebay.com

Throttle Position Sensor Fits 2001-2007 Freightliner FS65 Dorman 738LG32 | eBay

Throttle Position Sensor. Throttle Sensor Service Kit. 2022 DT Auto Parts Inc.

www.ebay.com

 

[FawnaFox]

ok, but, you still didn't explain how you checked it. this is important.

Post 317 of the thread had the diagnostic testing procedure for a aps/ivs circuit. Yes this is for international but the sensors are all just about the same. I will try to verify if Freightliner is different but for now, look t your voltages. Losing the 12v to the sensor is very common.

I go to go out now but when I get back I will try to verify more.

post #17

Slow/dead pedal at startup

So I got an interesting issue going on my 2nd bus, which I call the milkshake bus. It's a 2006 Amtran RE, DT466e/md3060. I did an in-frame on it last year and successfully drove the bus from Miami to Central Texas, pulling a toad, with no issues whatsoever. 65-70 MPH all the way! When I got...

www.skoolie.net

Throttle Position Sensor Fits 2001-2007 Freightliner FS65 Dorman 738LG32 | eBay

Throttle Position Sensor. Throttle Sensor Service Kit. 2022 DT Auto Parts Inc.

www.ebay.com

Ah ok, thanks, I will go out and check that when I get home from the store.

 

[ewo1]

Cummins - APPS Reset Procedure
This procedure has shown to help 24 valve ISB engines. It is basically teaching the fly by wire accelerator on these trucks to reread the position of the pedal and it's limits. Most complaints this will help with is poor acceleration, improper shifting, bucking in 5 and 6 speeds. Has been known to increase fuel mileage in some instances.

1. Set parking brake
2. Disconnect negative battery cables on both batteries
3. Turn ignition key to run(to drain any remaining capacitors)
4. Let truck sit for 30 minutes( this is the recommended minimum)
5. Return ignition to OFF position
6. Reconnect both batteries and secure, not a timed event
7. Turn key to run position(not start) and depress accelerator pedal slowly all the way to the floor
8. Allow pedal to return to top position slowly
9. Turn ignition switch OFF
10.Release parking brake

 

[ewo1]

Accelerator Position Sensor (APPS) Signal Voltage Too Low

APPS voltage input below the minimum acceptable voltage.

Monitor & Set Conditions
Accelerator Pedal Position Sensor (APPS) voltage is monitored when engine is running. DTC may be stored if low voltage is detected on APPS signal circuit or low voltage is detected between Engine Control Module
(ECM) and Powertrain Control Module (PCM).

Possible Causes

• 5-volt Supply At APPS Shorted To ECM Sensor Ground
• APPS Signal Circuit Shorted To ECM Sensor Ground
• 5-volt Supply To Ground
• APPS Signal Circuit Shorted To Ground
• APPS Signal Circuit Open To ECM
• PCM (APPS) Short To ECM Sensor Ground
• ECM (APPS) To PCM (APPS) Circuit Shorted
• ECM (APPS) To PCM (APPS) Circuit Open
• Short To ECM Sensor Ground
• Accelerator Pedal Position Sensor (APPS)
• Engine Control Module
• Powertrain Control Module

Testing
1. Turn ignition on with engine off. Using DRBIII(R) scan tool, check for ECM and PCM DTCs. Determine
if DTC is set by ECM or PCM. If DTC is set by ECM, go to next step. If DTC is not set by ECM, go to
step 7 .

2. Turn ignition off. Disconnect APPS sensor harness connector. APPS is located on bracket, just above fuel
injection pump. Turn ignition on with engine off. Using DVOM, measure voltage between cylinder block
(ground) and terminal No. 5 (Dark Blue/White wire) on APPS harness connector. If voltage is greater
than 4.5 volts, go to next step. If voltage is 4.5 volts or less, go to step 6 .

3. Turn ignition off. Ensure APPS harness connector is still disconnected. Check for continuity between
terminal No. 4 (Black/Yellow wire) and terminal No. 5 (Dark Blue/White wire) on APPS harness
connector. If continuity does not exist, go to next step. If continuity exists, repair short between Dark
Blue/White and Black/Yellow wires. The Black/Yellow wire is the sensor ground circuit.

4. Ensure APPS harness connector is still disconnected. Disconnect ECM harness connector. ECM is
located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector.
Check for continuity between terminal No. 4 (Black/Yellow wire) and terminal No. 3 (Light Blue/Black
wire) on APPS harness connector. If continuity does not exist, go to next step. If continuity exists, repair
short between Black/Yellow and Light Blue/Black wires.

5. Ensure APPS and ECM connectors are still disconnected. Check for continuity between ground and
terminal No. 5 (Dark Blue/White wire) on APPS harness connector. If continuity does not exist, go to
next step. If continuity exists, repair short to ground in Dark Blue/White wire.

6. Turn ignition off. Ensure APPS connector is still disconnected. Disconnect ECM harness connector. ECM
is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector.
Check Dark Blue/White wire for continuity between terminal No. 5 on APPS harness connector and
terminal No. 31 on ECM harness connector. If continuity does not exist, repair open in Dark Blue/White
wire. If continuity exists, replace and program the ECM. See appropriate REMOVAL, OVERHAUL &
INSTALLATION article.

7. Turn ignition off. Disconnect PCM harness connectors. PCM is located at passenger's side rear corner of
engine compartment. Check for continuity between ground and terminal A23 (Orange/Dark Blue wire) on
PCM harness connector (APPS circuit). If continuity does not exist, go to step 9 . If continuity exists, go
to next step.

8. Disconnect ECM harness connector. ECM is located on driver's side of engine, just in front of fuel
transfer pump and contains a 50-pin connector. Check for continuity between ground and terminal A23
(Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If continuity does not exist, test is
complete. If continuity exists, repair short to ground in Orange/Dark Blue wire.

9. Ensure PCM harness connectors are still disconnected. Disconnect ECM connector. ECM is located on
driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. Check for
continuity between ground and terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS
circuit). If continuity does not exist, go to next step. If continuity exists, repair short to ground in
Orange/Dark Blue wire.

10. Check Orange/Dark Blue wire for continuity between terminal No. 5 on APPS harness connector and
terminal No. 31 on ECM harness connector. If continuity does not exist, repair open in Orange/Dark Blue
wire. If continuity exists, go to next step.

11. Reconnect ECM harness connector. Ensure PCM harness connectors are still disconnected. Turn ignition
on with engine off. Using DVOM, measure voltage between ground and terminal A23 (Orange/Dark Blue
wire) on PCM harness connector (APPS circuit). If voltage is greater than 0.4 volt, test is complete. If
voltage is 0.4 volt or less, go to next step.

12. Turn ignition off. Disconnect APPS harness connector. Check for continuity between ground and
terminal A23 (Orange/Dark Blue wire) on PCM harness connector (APPS circuit). If continuity does not
exist, replace APPS. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If
continuity exists, replace and program the ECM. See appropriate REMOVAL, OVERHAUL &
INSTALLATION article.

 

[ewo1]

Let me say that it is real hard/impossible to find freightliner manuals on the web...
Best I can do right now for wiring, ISB WIRING, is this ...so far...

top left you will find the pedal sensor, two different styles listed.
can you post a pic of yours, how many wires on the connector and how many pins in the sensor?

 

[BamaBus]

I have a 1999, 2000 and 2002 ISB 5.9 (FS65 and BB TC1000) and they do not the APPS above the VP44 as the Dodge's do. Where is it? Beats me.

 

[ewo1]

I have a 1999, 2000 and 2002 ISB 5.9 (FS65 and BB TC1000) and they do not the APPS above the VP44 as the Dodge's do. Where is it? Beats me.

look at the top of the gas pedal.... anything there?
International identifies it as APS/IVS
Cummins identifies it as APPS

 

[ewo1]

I was taking a closer look at the Cummins ISB wiring (post "8") and it appears to me that your TPS is operated by +5v and ground.
there are 2 circuits inside the TPS just as in the Internationals.

looking at the 6 pin (1 connector) wiring versus the 2 connector wiring. Your pic of the pedal, I only see one connector.

Circuit #1 - Accelerator position circuit. This is nothing but a variable resistor, just like in the old school boom box radio volume control. As you step down on the pedal the resistor value increases changing the voltage level signal that goes to the ECU which in turn provides more fuel to the engine and RPM'S go up.
The input voltage is only 5v.
If you have cummins Insite you will be able to see this movement within the diag software. The signal return is actually your signal ground to the ECM not the bus Chassis/frame.

Circuit #2 - The second half of your switch is your idle control circuit. Idle ON or idle OFF. simple!
this half of the circuit operates differently than that of the Internationals.
In the Internationals it sees and is controlled by 12v.
In the Cummins it is Ground activated.

Looking at the wiring diagram, ISS connector pin "F" is where the ground originates.
This is Battery ground or chassis ground and not signal ground!
When you step on the pedal, the sensor switches from "E" to "D". this tells the VP44 pump that it it ready to start rolling! Engine rpm increase via circuit #1.

I am not there at your bus but this is what I suspect is going on.
The sensors just usually FAIL. either circuit 1 or circuit 2 resulting in no throttle response.

I get the impression your bus still drives but you are having an intermittent issue. Sometimes it works and sometimes it does not. Is this what is going on?

If so I would look at your ground circuit. where does this "F" ground wire connect to the battery/frame ground?

I would be suspicious of a failing connection. This is what I would check on and eliminate first!
What I would do if I was in your shoes is to load test that ground wire and not just simply test with an ohmmeter.

A simple load test would be an 1156 light bulb, one side go the wire on "f" and the other side to the battery 12v.
If the light is bright then you have a clean ground connection. If it is not bright but is yellow or dim, you have a poor ground connection.

this is what I would do first because if you change the sensor and keep the poor connection, you have accomplished nothing and spent some money.

hope this helps...

 

[ewo1]

Here is a 2003 Bluebird throttle control circuit for a Cummins engine. Same circuit as i describe above.

The 12 v battery:
notice that the negative (ground) of the battery, that wire goes to feed the TPS which in turn provides the proper ground or no ground for the idle circuit.

 

[ewo1]

My 98 FS-65 has random instances where the throttle stops responding. I know that it’s the TPS (throttle position sensor) and I need a new one. What part do I need? All I know is that the throttle pedal is made by Williams Controlls.

I didn't even address your original questions, TPS sensors is easy to replace. get the part number from the one you have now.
I got mine from these guys,

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