Engine/Transmission (1998.5 - 2002) Problem with MOPAR Jacob Brake PN 82205577

[rapidscat]

Installed new brake on my 2001 Dodge 6 speed. Everything works fine EXCEPT after about 2 hours of highway driving or 120 miles unit stops working. IF I pull over and turn off truck off and restart it works fine for approximately another 2 hours or 120 miles.



I do have have fuel pressure gauge, pyrometer, and boost gauge all are Issopro. Fuel pressure is the only one that concerns me. Idle 10-12 PSI. Running 7 PSI. Could low fuel pressure be my issue.



I have owned truck since new. ECM has never been replaced or serviced.



ANY ideas why this would happen?

 

[HBarlow]

Your truck has a failing APPS. I had the same problem years ago when my '01 was new. What happens is you're running along the highway with cruise control set and click off the cruise to slow and the exhaust brake won't activate. This happens because the APPS is still sending a signal other than "0" idle speed to the ecm and the signal to activate the exhaust brake comes from the ecm.

A similar thread was posted a month or so ago. Same symptom, same cure.

 

[JLandry]

If it is a problem with the APPS idle validation logic, then there should be a trouble code set in the ECM.



Check for stored trouble codes in the ECM with a good code scanner.



John L.

 

[JLandry]

rapidscat,



Where are you located (in case someone close by can help)?



Please fill out your profile.



Best regards,



John L.

 

[HBarlow]

My guess is the bad apps will not set an ecm trouble code. The '01 ecm was much smaller and simpler than the Gen III and Gen IV trucks are now.

 

[JLandry]

My guess is the bad apps will not set an ecm trouble code. The '01 ecm was much smaller and simpler than the Gen III and Gen IV trucks are now.

It should... I've had it happen several times when the original APPS on my truck started going bad. It set the MIL (Malfunction Indicator Lamp).

Here are the relevant DTC's:

P-0121-ACCEL POS SENSOR VOLTS DO NOT AGREE W/IDLE VALID SIGNAL
P-0122 ACCELERATOR POSITION SENSOR (APPS) SIGNAL VOLT-AGE TOO LOW
P-0123 ACCELERATOR POSITION SENSOR (APPS) SIGNAL VOLT-AGE TOO HIGH
P-0222 IDLE VALIDATION SIGNALS BOTH LOW
P-0223 IDLE VALIDATION SIGNALS BOTH HIGH (ABOVE 5V)
P-1286 ACCELERATOR POSITION SENSOR (APPS) SUPPLY VOLTAGE TOO HIGH
P-1295 ACCELERATOR POSITION SENSOR (APPS) SUPPLY VOLT-AGE TOO LOW

Best regards,

John L.

 

[PC12Driver]

My Jacobs ex-brake went through a phase where it was sticky. A couple hours on the highway would give it a good heat soak and it wouldn't close. A tap on the actuator arm with the engine idling and the brake switch on would free it up and it would work again. It stuck a few times for me, but it eventually grew out of it.

Start simple and work your way back. Next time it isn't working, don't shut it off and try a few things. Try the tap like I explained above. Pull off the hose from the exhaust brake solenoid valve and see if it is sucking. Keep a multi-meter handy and check to see if the solenoid valve is getting voltage. No voltage at the valve, then check at the switch. Make sure the brake's power supply pin is seated in the ECM plug firmly. Check the ground wire coming off the solenoid valve for good contact. If there isn't voltage being supplied from the ECM, then start to check the expensive stuff.

If it is a new brake and you aren't seeing any other secondary symptoms with the rest of the truck (funny or high idle for example), it could just be a simple matter of the brake's parts not being machined properly and they're binding after they get heat soaked.

 

[rapidscat]

reply

Thank you for the assistance.



I am located in Twin Cities Minnesota area.



I have never had any error codes on truck. ECM has never been serviced.



More information. The 2 hours of driving / 120 miles cruise is on. Should I attempt to drive 2 hours without cruise on?



If truck has a failing APPS - the corrective action is what? What checks are possible? What was the name of other thread posting?



The Truck runs fine gets great with no issues. EXCEPT for brake not working...



Analysis -

1. Ground wire is to battery ground with continuity.

2. Tried tapping on actuator arm no change. It is in the OFF position. Thus spring loaded it pulls back for off position. Vacuum actives valve to on.

3. ECM wire securely seated.



4. I will check voltages.

5. I will check vacuum.



5. If I pull over, turn engine off, and I immediately restart - (truck has traveled about 2 hours/120 miles. Thus truck at operating temp and well heat soaked) Valve works again for 2 hours or about 120 miles.



I have about 1500 miles on brand new brake unit. About 75k miles on truck. yes, truck is like BRAND new. Never driven in snow and only caught in the rain. It is used as long distance car hauler.

 

[ScottLewis]

Does the 2001 have an EGR on it? Just wondered since my '98 had a problem with the Banks exhaust brake when I first installed it that acted a bit like this. When the EGR activated it bled off the exhaust pressure.

 

[HBarlow]

It should... I've had it happen several times when the original APPS on my truck started going bad. It set the MIL (Malfunction Indicator Lamp).

Here are the relevant DTC's:

P-0121-ACCEL POS SENSOR VOLTS DO NOT AGREE W/IDLE VALID SIGNAL
P-0122 ACCELERATOR POSITION SENSOR (APPS) SIGNAL VOLT-AGE TOO LOW
P-0123 ACCELERATOR POSITION SENSOR (APPS) SIGNAL VOLT-AGE TOO HIGH
P-0222 IDLE VALIDATION SIGNALS BOTH LOW
P-0223 IDLE VALIDATION SIGNALS BOTH HIGH (ABOVE 5V)
P-1286 ACCELERATOR POSITION SENSOR (APPS) SUPPLY VOLTAGE TOO HIGH
P-1295 ACCELERATOR POSITION SENSOR (APPS) SUPPLY VOLT-AGE TOO LOW

Best regards,

John L.

I experienced multiple apps failures on my '01 during 325k miles. It never set a cel or mil. On a couple of occasions the apps went completely dead. It ignored my throttle pedal foot entirely. Never gave any indication other than non-response to the pedal.

 

[PC12Driver]

If truck has a failing APPS - the corrective action is what? What checks are possible? What was the name of other thread posting?

The APPS is no big deal to swap (less than an hour). Geno's has one for a good price. Since your truck doesn't have a vacuum cruise control actuator the swap is that much easier.

Don't panic. Start simple. You have no other indications that you have anything else wrong other than the exhaust brake stuff. Cross the APPS bridge if the other tests point to it.

 

[HBarlow]

I posted the basic, simple step for testing the exhaust brake to determine the problem was caused by the apps in the other post, same subject.

OP. do a simple search. It'll show up.