98.5 24v Power/electrical trouble

Hey everybody. I have a 1998 Ram 2500 24v Cummins with an auto trans. 235,000 mile stock truck, only additions include Fass lift pump, gauges (trans temp, fuel pressure, and boost), and a Smarty.

Two days ago driving up a hill and was motoring along until the rpms dropped by around 300rpm, bounced back and then I had a check engine light on and poor power. I checked the codes with the Smarty and found the following:
P0237 map sensor voltage too low
P0602 ECM Fueling Calibration error
P1693 DTC Cleared in companion JTEC module

I reset the ECM back to stock tune, eliminating the Smarty, and cleared the codes.
Today the CEL came back on and I read it with an OBD2 scanner this time and found the following:
P0237: low voltage map sensor
P0122: low voltage accelerator position sensor
P1389: no auto shut down relay output voltage at PCM
P0720: output speed sensor malfunction

I cleared the codes again after checking on the connections, quick glance found no issues and just sprayed electronics cleaner. I drove about 60 miles tonight without the light coming back on but I am having trouble getting up to speed and maintaining speed. Low boost output and poor acceleration until I put my foot to the floor. Found no boost leaks while I was in the engine bay either. Fuel pressure ~19psi at idle and doesnt drop below 15psi at WOT. I am at a loss on where to start. Any help is appreciated.

P0237 Turbo Charger Boost Sensor A circuit low. Clean it with air intake cleaner, not brake kleen

P0122 - 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.


Also try this:

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




DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM

1. Turn ignition on with engine off. Using scan tool, check for DTCs. If DTC SPECIFIC GOOD TRIP counter is not displayed and equal to zero, go to next step. If DTC SPECIFIC GOOD TRIP counter is displayed and equal to zero, go to step 4 .

2. Ensure ignition is on with engine off. Using scan tool, check for DTCs. Check that displayed DTC matches the FREEZE FRAME DTC. If DTCs displayed are the same, go to next step. If DTCs displayed are not the same, perform procedures for FREEZE FRAME DTC.

3. Using scan tool, check for DTCs and record FREEZE FRAME data. Try to duplicate conditions recorded in FREEZE FRAME data. Using scan tool, check for DTCs. If DTC SPECIFIC GOOD TRIP counter changes to zero, go to next step. If DTC SPECIFIC GOOD TRIP counter does not change to zero, go to step 7 .

4. Turn ignition off. Remove ASD relay from power distribution center. See Fig. 54 . Power distribution center is located at driver's side front corner of engine compartment. Note cavities in power distribution center for ASD relay. See Fig. 54 . Using voltmeter, check voltage at cavity No. 30 (Red/Light Blue wire) in power distribution center for ASD relay. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open between battery, fuse No. 6 (30-amp) and Red/Light Blue wire between fuse No. 6 in power distribution center and cavity No. 30 in power distribution center for ASD relay. Perform TEST VER-2A .

5. Ensure ignition is off and ASD relay is still removed from power distribution center. Disconnect PCM connectors. PCM is located at passenger's side rear corner of engine compartment. Using ohmmeter, check resistance between cavity No. 87 (Dark Green/Orange wire) in power distribution center for ASD relay and terminal No. 12 (Dark Green/Orange wire) on PCM connector C3. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Dark Green/Orange wire between PCM and cavity No. 87 in power distribution center for ASD relay. Perform TEST VER-2A .

6. Ensure ignition is off. Install a substitute ASD relay. Using scan tool, clear DTCs. Start engine and allow engine to idle. Using scan tool, check for DTCs. If DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM exists, replace PCM. Perform TEST VER-2A . If DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM does not exist, replace original ASD relay. Perform TEST VER-2A .

7. Using scan tool, clear DTCs. Start engine and allow engine to idle. Wiggle wiring harness and connectors between ASD relay and PCM. The ASD relay is located in power distribution center at driver's side front corner of engine compartment. See Fig. 54 . PCM is located at passenger's side rear corner of engine compartment. Using scan tool, check for DTCs. If DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM does not exist, go to next step. If DTC P1389: NO ASD RELAY OUTPUT VOLTAGE AT PCM exists, repair wiring harness or connectors between ASD relay and PCM that caused DTC. Perform TEST VER-2A .

8. Shut engine off. At this time, conditions required for DTC to be stored are not present. Inspect wiring harness and connectors between ASD relay and PCM. If no problems exist, go to next step. If any problems exist, repair wiring or connectors as necessary. Perform TEST VER-2A .

9. Problem is intermittent. Inspect PCM connectors for corroded, pushed out or damaged terminals. Inspect wiring harness and connectors between ASD relay and PCM for chafed, pierced or partially broken wires. If terminals are not corroded, pushed out or damaged and wiring is okay, check for Technical Service Bulletins (TSBs) that may apply. If terminals are corroded, pushed out or damaged, or wiring is damaged, repair as necessary. Perform TEST VER-2A .

SYMPTOM
P0720-LOW OUTPUT SPEED SENSOR - RPM ABOVE 15 MPH

WHEN MONITORED
Continuously with the ignition on, engine running, and gear selector NOT in park or neutral.

SET CONDITION
This DTC will set if the vehicle speed (reported from the CAB module) is above 24 Km/h (15 MPH) , and the monitored Output Shaft Speed is below 60 RPM for 2.6 seconds .

POSSIBLE CAUSES

• Park/neutral DTC present
• Intermittent wiring and connectors
• Output speed sensor ground circuit open
• Output speed sensor signal circuit open
• Output speed sensor ground circuit shorted to other circuits
• Output speed sensor signal circuit short to ground
• Output speed sensor signal circuit shorted to other circuits
• Output speed sensor ground circuit short to voltage
• Output speed sensor signal circuit short to voltage
• Output speed sensor
• ECM

if this is the ONLY code you have, I would say check the wiring at the speed sensor



This is from some of my notes regarding these codes I have seen prior some may be a copy paste from elsewhere. They seem to be all over the place and I am not sure where to look honestly. I would try the apps reset procedure, and see what happens. @Polaraco any ideas? just let us know what you find after that @smorella24v

Thank you @F350Cummins, I'll give the APPS reset a try and then move down the line and keep you posted.