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P1689 - 1999 Ram 2500 - Idle @ 800rpm & start easy- touch pedal rpm jumps to 1400????

balesray
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dripley

dripley

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ECM and reasonable price dont normally work in the same sentence. I replaced mine with a Cummins reman for $1400 installed and program from a shop in Bolivar TN. There was thread on here a month or so ago with a source for a reman around $800 but i cant find it. Maybe some one else can. It looked like a good clean unit compared to my experience. It would come programmed and you would have to install but that is easy. Anybody know where to find that thread?

 

The experience I had first was with an internet re builder. The Cummins reman came a year later.

Edited by dripley
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balesray

balesray

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ECM not the problem.  Truck still performs exactly the same with new ECM so what to do next???  I have a couple of questions hope someone can help with.

1.  How many inputs are connected to the ECM ?

2.  If any of these inputs are defective what will be the trouble that shows there is a problem?

3.  Will any of these inputs cause the ECM to not function correctly?

4.  Wiring diagram shows an electrical connection between the ECM and PCM on these trucks.  What is that for?

5.  Someone said to much ripple on the dc voltage coming from the alternator can ruin the ECM.  If so what is the results?6.

6.  What should be the maximum voltage coming from the alternator?

That is a start.  More to come & hope not creating a problem for anyone.

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Me78569

Me78569

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1. iat, map, crank, cam, oil press, ect, app,s think that's it...think

2. apps would be my first guess.

3. not really the ecm will take in bad info. truck might not run, but the ecm doesn't really throw a hissy fit if something isn't right

4.ccd and sci bus to allow communicaiton between the pcm and ecm for things like revs to cluster, coolant etc.

5. When you have too muhc AC noise from the alternator strange stuff happens.

6. typically we want to see under .03v ac 

 

 

do you still have the 1689 code?  

 

 

Have you done an apps reset?

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balesray

balesray

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Is that what is called PSG on the VP44 and can it be repaired.  Noticed there is a place in England that says they repair the PSG5 in the VP44.  Just wondering if this is possible and if there is any place in the states that does this?  Thanks

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balesray

balesray

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What are the symptoms if the map sensor quits working properly.  Does this have any effect on the operation of the engine.   Thanks for replying again.

One of the pins going to the APPS is labeled "low idle select".  Does anyone know what that signal is and what it is for?????

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Dieselfuture

Dieselfuture

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I've read on bluechip's site that pretty much most of original vp psg's were failing do to lead free solder and too many heat cycles. and internals were not quite as good as they are now. there are some people that claim transistor fails in vp psg's and can be fixed, but I think I would just get a reman one and upgrade fuel system like previously mentioned and move on. 

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balesray

balesray

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If the MAP sensor output voltage reads 5 Volts DC which is the same as the input voltage would indicate that this sensor output is shorted to the input.  What effect will this have on how the truck will runs???  Would like to know.

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Me78569

Me78569

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If the output voltage is 5v you will have a high psi situtation reported to the ecm.  I doubt this would make the revs jump like that.  Iam still mostly concered with the p1689 code.  That specifically means the ecm cannot talk to the vp44.  Unplug the map and see if your truck is better, it will throw a code, but effectively it just runs as if there is 0 boost.  

 

The vp44 can idle on it's own without talking to the ecm.  That is what the idle sense wire is for.  Think of idle as a "closed loop" type situation. as soon as tps input is sensed it will jump out of idle state and the ecm will start to command fueling. 

 

Now if your sensors are shorting to ground etc I could see the ecm getting pissed off and not being able to command fueling.  

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