Hello to the good people of mopar1973man.com! I am very new to this site as far as having a account but have been a avid "user" for some time now. I figured it may be time to settle in after the site change. Looking forward to helping where i can and learning a few things aswel!

Anyways, on to whats fun and exciting Please allow me to unravel my situation. I have a 1998.5 Dodge ram 2500 5spd 4x4 (vp44, vin 6) that is throwing one ecu code. P0123. I have read the write up on mopar1973man.com regarding this code. The resulting symptoms consisted of dead pedal, intermitent throttle response, the truck reving on its own only when i touch the throttle. I have scoured the internet, service manuals and shops in search of any help or advice as to why this code is appearing. Apps and ecu are what i hear usually. In pursuit of finding a solution  i removed the engine wiring harness, ecu, inspected every wire and connector and checked each wire for resistance. I found no resistance. Cleaned each connection, ground and reinstalled the harness. Then set the apps voltage via the adjustment screw on the new apps sensor i installed.  Connected the batteries, set the apps via throttle pedal and fired up the truck and it ran great. No problems or codes at all for a week. I then parked the truck for approximatly a month. Today i started the truck and experienced the exact same symptoms as before. My first instinct is to check the harness again but would like to hear what you good folks have to say. Has anyone else encountered this issue before?

Thanks, James

 

If you already done this testing then you might consider replacing the APPS with a timbo's APPS.

What would be the purpose of using timbos apps compared to a replacement? I understand its a better quality unit but what will that change signal wise?

5 hours ago, Mopar1973Man said:

 

If you already done this testing then you might consider replacing the APPS with a timbo's APPS.

What would be the purpose of using timbos apps compared to a replacement? I understand its a better quality unit but what will that change signal wise?

58 minutes ago, toesovernoes said:

What would be the purpose of using timbos apps compared to a replacement? I understand its a better quality unit but what will that change signal wise?

No change signal wise just no electronics in the timbo.

Stock OE APPS sensor.

Timbo is completely mechanical switch no electronics at all. So less to go wrong.

 

I need to get a Timbo

On ‎24‎/‎02‎/‎2016 at 11:33 AM, Mopar1973Man said:

No change signal wise just no electronics in the timbo.

Stock OE APPS sensor.

Timbo is completely mechanical switch no electronics at all. So less to go wrong.

 

I am currently in the process of following the testing procedure on the p0123 article. So far I have found no continuity between terminal No. 4 on APPS harness connector and terminal No. 32 on ECM harness connector. This leads me to believe I have a intermittent opening in the engine harness somewhere.

So you got a bad ground lead from the APPS to ECM.

On 25 February, 2016 at 2:41 PM, Mopar1973Man said:

So you got a bad ground lead from the APPS to ECM.

I have since repaired the ground and have continuity. I was having the same issue but luckily i found a identical ecu for the truck so i took a chance and bought it. installed it, calibrated the apps and the truck ran great so i took it for a spin. Runs just like nothing ever failed in the first place. 

Then last night i took it out again for a spin up a logging road near my buddys house. Truck died. No codes, no shutter or misfire just like someone turned off the key. Checked the fuses, swapped some relays around, lift pump was running, fuel at the injection pump, good pressure, cranked and cranked but didn't catch. So we used the starter to turn the truck around and coasted back down the mountain. After about 15 minutes i tried starting again and it caught? Weird!  Drove it home and parked it for the night. First thoughts are injection pump or wiring connections but no codes appeared. Dirt in fuel maybe? Seized pump rotor? Crank sensor?

Truck has started and has run awesome today. Time to get the ou the pressure gauges and dvom.

1 minute ago, toesovernoes said:

Dirt in fuel maybe?

Filter should of caught the dirt in the fuel.

1 minute ago, toesovernoes said:

Seized pump rotor?

It would of broke the plate in the pump for the rotor and never ran again. 

2 minutes ago, toesovernoes said:

Crank sensor?

Is the alternator charging and is the tach working? Any P0336 or P0341 codes?

 

7 minutes ago, Mopar1973Man said:

Filter should of caught the dirt in the fuel.

It would of broke the plate in the pump for the rotor and never ran again. 

Is the alternator charging and is the tach working? Any P0336 or P0341 codes?

 

Alternator is charging, tach is working, no CEL. ill get out the code reader.

You definitely dont have to have a CEL for codes to be present.

On Monday, February 29, 2016 at 6:18 PM, dripley said:

You definitely dont have to have a CEL for codes to be present.

Hooked up the scanner and have no codes present. Truck hasnt skipped a beat since.

I haven't been here in a long time but i figured i would button up this thread if anyone else is looking for information about the same issue. So shortly after my last post,  sometime in March,  the injection pump died. The computer on the pump failed, so i bought a unit from DAP and have had zero issues since. Not bad considering it was the original injection pump with 360,000kms. 

 

Edit. To add i also ran the truck with the new pump and a replacement tps for month before i put in a Timbo tps. Dont think just buy the Timbo TPS.

Edited November 11, 20168 yr by toesovernoes
More info

I highly suggest you do a AC noise test on the truck if the VP44 failed. If you don't resolve that issue the new VP44 will go down that road again and fail.

 

 

Edited November 11, 20168 yr by Mopar1973Man

On Friday, November 11, 2016 at 7:18 AM, Mopar1973Man said:

I highly suggest you do a AC noise test on the truck if the VP44 failed. If you don't resolve that issue the new VP44 will go down that road again and fail.

 

 

I will do so. I am not currently driving the truck so i will have some time over the winter to do some testing. 

I did the ac test as per the write up and came up with 0.00 to 0.02 ac volts. I hope to start building a flatdeck for my truck in the coming weeks and get away from all this diagnostic work.