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Will it run without a PMD resistor?

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5akman

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My '96 work truck in AK stopped running last summer. The prior owner had what looked like a new PMD in a box in the glove compartment so I purchased a heat sink and extension harness off flea bay and mounted it under the bumper. It ran fine for the rest of the summer, almost. It then was either hard to start or would start and then would die just like when the PMD was going bad. Now that I think about it, I didn't have a resistor to install with this PMD. Would the truck not run after a bit of time (or X number of starts) if the resistor is left out of the circuit?

Lance
 
The truck will run without one, I dont have one on my wifes truck, After so many starts the computer will defalt to a 1 or a 5 IIRC
 
Has been talk on here that obdIs would be ok (default to a certain setting) but that obdII,s when a relearn was done ,after 50 starts or whatever may or or may not start.
 
I worked on a 2000 6.5 that had no resistor and had a code stating something about the injection pump resistor circuit and ran very very rough including missing and sputtering. I looked in the PMD on the intake and sure enough, no resistor.

I connected my Heath Isolator to that truck and started it up, didn't clear the code, and it ran perfectly.

That would tell me that OBDII needs a resistor. After the 50 key turns if it doesn't find one, it seems to freak out.
 
My 95 didn't have a resister in it and it ran rough and very loud clacking, kept sending a 35 code, put one in and very quiet smooth running, like it was a different engine. No codes since.
 
Diesel -T said:
Has been talk on here that obdIs would be ok (default to a certain setting) but that obdII,s when a relearn was done ,after 50 starts or whatever may or or may not start.
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My 97 has none and is fine
 
It was in a GM factory box and based on cleanliness (sp?), I assumed it was new. It does now run (or for that matter, not run), and acts like PMD problems I've had in the past on both trucks. I think I'll purchase a new PMD to try just in case along with a resistor. I hate to throw money away but when I get to AK each summer I have about 6 weeks to make my bankroll and there usually isn't much time for trouble shooting so remove and replace becomes common place..........
 
Just do all the common failure diagnostics first, before dropping coin on a PMD.....Fuel pressure, lift pump, grounds, OPS, etc......Although a spare PMD wouldn't kill you.
 
ak diesel driver said:
IIRC TD said he pulled his out for 6 months to prove a point he's got a 98
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OBD-II will run on previous stored value indefinately until a learn is commanded with a T-2 or a ko/ko APP to floor. OBD-Is are the ones that self learn after 50 warm up cycles and default to some value or so I have been told. OBD-II that have been commanded to learn the value without a resistor in the FSD/PMD socket will not start.
 
Turbine Doc said:
OBD-II will run on previous stored value indefinately until a learn is commanded with a T-2 or a ko/ko APP to floor. OBD-Is are the ones that self learn after 50 warm up cycles and default to some value or so I have been told. OBD-II that have been commanded to learn the value without a resistor in the FSD/PMD socket will not start.
Click to expand...

I don't know Tim. :confused:

That 2000 i worked on had no resistor and had a code stating such. The owner figured it was the IP with the way the truck ran. Very rough idle, totally un-driveable, the works. That's when I tried my Heath isolator on it to see if it was a PMD issue. When the truck ran fine at first i figured it was the PMD as it was a very poor mount choice on a piece of maybe 1/8" steel for a "heatsink". When i switched back to that PMD the truck still ran perfectly fine. I even drove it around town to make sure. It seems it stored the value of my #7 resistor in the Heath Isolator.

Thats the only way i can explain it. I can't think of any other way what i did would change the way it ran if it didn't need a resistor :confused:
 
We can assume the batteries were "disconnected" as the truck sits all winter long with no use (actually from mid Aug - July 1st when I fly up to work). Even though a friend is suppossedly keeping the batteries charged over the winter for me, when I arrived last summer the batteries were stone dead! If this then in anyway hampers the computer function, then perhaps its taking a "no resister" condition and opting not to run?

Lance
 
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