Michigan Ram

After wasting $165 on an APPS and another $110 on a new MAP (both threw codes & APPS checked bad per flowchart), still having the same erratic throttle problem . Codes also showed ECM and various voltage out problems, but was told could have been triggered by bad sensors. Now I think I'm down to bad ECM or loose/shorted wire (that I can't seem to find). Don't want to throw another $500 bill into the fire with a new ECM if there's anything else I haven't thought about. Anybody have any ideas?

About a week before problem happened, I replaced (auto) trans. Drove for about 4 days then problem hit. Rechecked all connections to and around trans and couldn't find anything loose, broken, etc. Can anyone help me on how to go about tracking ALL possible wiring ground/short problems? Not sure where all of them located that are associated with the ECM.

Thanx.

Lil Dog

Not sure if it would help, but did you try the resetting procedure for the APPS? This site might be able to help you out too.

http://www.dodgeram.org/support_pgs/diesel_ix.htm

Michigan Ram

Thanks for posting the link Lil Dog, that's got some helpful tips in there. I did try the reset procedure for the APPS (a couple of times) after I installed the new one. Didn't help unfortunately. I've convinced myself that it's either a bad connection/loose wire somewhere or the ECM. Just want to do everything I can before dumping more $$$ on an ECM only to find out later that it wasn't bad.

RRumwell

What "FlowChart"???

Mine has started just cutting out (down to idle) at cruising speed, has thrown no codes...

Last dead pedal issue turned out to be a clogged airfilter after a edit pile of diagnosing and trips to the ***********.

Need to effeciently diagnose the problem.

RR
'03 QCLB 4*4 XLT Lariat: Diablosport, 1-piece driveshaft, ToyoMT, Ansa Silverline, K&N, etc...

dsldan

Might want to try unpluging and reseating all connectors with dialectric grease.

Thundercraft

certainly can't hurt and it's inexpensive too

nickg

dirty battery commections/ or the grey connectors found on the negative battery cables will send the ecm into a tizzy, maybe "borrow" someones ecm to see if that fixes it.

possible bad injector will cause bad idle as well, maybe you have a mechanical issue.

blue chip has a really good diagnostic chart to follow when diagnosing a vp.

here is the link

http://www.bluechipdiesel.com/vp44diagnostichelp.html

RRumwell

OK, now I'm on to something, and maybe somebody can point me at the right thread which I haven't been able to locate by search...

Dead Pedal, ONLY when running AC... No codes...

The dreaded dead pedal came back, and I finally figured out that it only happens with the AC running. I seem to remember reading somewhere that there can be a voltage issue with AC and APPS?

Thanks if you all could help out.

RR
'03 Ram Cummins HO 4*4 QC LB Lariat (1 piece drive!!!! best mod ever)
Timbo APPS
Updated lift pump
etc...

rickf

I am not in front of the my truck or a diagram but do they both use the same ground? If so check that. The throttle position sensor is mechanical so there should not be an electrical interference issue. It sounds like a resistance issue.

Rick

pind

Check under the AC compressor, where the wires run against the compressor body. This is an area that is know to rub through and short to ground. This could cause your issue

RRumwell

No luck on finding the wire by the AC compressor, I only see the wires going into the compressor, and those look fine.

The mystery continues... Will be trying di-electric grease on some connections just because, but don't expect much.

RR

RRumwell

This will eventually drive me crazy. Somebody must have had the same experience... It is 100% reproducible, turn off the AC and it never happens. AC On and it's sporatic...

RR

Sootblower

Does it happen when the A/C compressor clutch disengages? If it does I would look at the diode that is across the clutch coil in parallel. This diode prevents high voltage impulses in the electrical wiring and that APPS sensor is close-by.

When you open an inductive (magnet coil)circuit you get a huge voltage and arcing that would eventually destroy the A/C relay contacts. The diode quenches that voltage.

You can see how often the compressor engages while idling and it will be slightly shorter cycle while driving at higher RPM or alternately wire an LED w/series resistor in parallel with coil and wire back to passenger compartment and correlate it to the symptom.

Busboy

Pind probably has it right, check again the wires going from the low pressure and high pressure switches for the AC the voltage is only 5 volts, the same as the apps and any intermittent shorting will lower the apps voltage.

RRumwell

Y'all won't believe this....

So, after just saying *** and driving around with no AC for the last two years (unplugged the AC compressor wires), finally the blower motor quit also...

So I finally got a tech who could solve the problem.

Turns out the clutch on the AC compressor shorted out in a way that it was back feeding voltage up the wires!

Wires shot, resistor pack shot, more wires shot to blower motor.

New compressor and clutch, new wiring, new blower motor, new resistor pack, more new wiring, all done and fixed.

Just thought I'd post this so y'all could laugh at me for putting off this for soo long.

All it takes is 1day driving across WA state at 101deg to push me over the edge to open my wallet to "whatever it takes"!

RR