PDM Resistor Purpose

[ryno]

I replaced the injection pump and PDM module on my 1995 6.5 TD. I did not have it timmed, but it ran fine...great really. For about a week and then it began stalling, or should I say just shutting down. The new injection pump came with a new pdm module and I did not pull the resistor out of the old. If the new PDM did not have a resistor what would this cause the truck to do? Can I buy a new resistor for the PDM at the dealer? I have read before that there are different resistor types? Is this true? Which one do I need and why

[JohnC]

The resistor value is tied to the pump. The new pump should have come with the correct resistor already installed. When you get it timed, if it doesn't generate a code for the resistor, you're good to go.

[ucdavis]

Resistor suposedly adjusts for electronic differences between ndividual IPs and each one is supposed to get the exact specific rated resistor (numbered 1 thru 9) to do that. In reality many here have used the #5 cuz its in the middle & it works fine. Others use a #9 cuz it equates to about 2mm more fuel rate (probably @ WOT) which nobody can feel by the seat ofthe pants.
If I was being you, I'd pull the old resistor out & install it in the new setup; the PCM "looks" for the resistor value periodically & sets a code if its missing, but uses the last resistor value stored till it re-reads the current one.
However, that doesn't sound like your problem. How about a complete rundown on what you changed out, why, mileage on rig, any mods that might affect drivability, etc.?
Read your DTC codes & post those, "none" if that's the case: http://www.thedieselpage.com/members/trblcode.htm

[ryno]

The truck has 240,000Km on it. It has a Power Chip, 3" Down Pipe and Exhaust, K&N filter, and Exhaust Brake. I replaced the lift pump, along with adding another after market lift pump that runs as long as the ignition is turned on. Replaced the fuel filter, disconnected the lift pump, disconnected the oil pressure switch, removed air from the fuel filter and still the truck shuts down with out warning. This is what it did when it first began acting up, only it set codes before. Put the new injection pump in and it ran great for only a week or so and now is shutting down again, with no codes. I think the pump may have been faulty. I have got a new one I am going to put in today.

[gmctd]

PCM will set code 56 if the resistor is missing or open, and will default to the lowest fuel table.
Driveability may suffer, but not to extent of shutting the engine down.
PCM will learn the new resistor value next time the engine is started.
As stated above, new pump and FSD\PMD has resistor installed.
New FSD\PMD does not - requires installing the resistor from the original driver, which will be calibrated for the original FI pump.

jd

[G B Sisson]

Very interesting reading all you folks! I seem to have solved my "sudden death syndrome" stalling last week with the installation of a new PMD and cooler on manifold. I called Bill Heath to get his 6' extension harness so I could move my cooler out of the hot engine compartment and away from engine vibration. As I now want to carry a spare PMD,I decided to buy his whole remote setup. I asked him about resistor with this long harness and he said they have always used the #9. They have been building this same setup since '94. Theirs is mounted to a large aluminum plate and he always mounts them to the 4wd skid plate,he includes a drilling template.He claims that this #9 resistor gives a little more fuel and I asked him if thats better why didnt they all run like that? He said it was about emissions. I dont have emissions test in my area so I guess Ill run with it....So far 2 PMD kits,but Ive still spent less than half of what chev dealer quoted me for his IP replacement... Any thoughts on this # 9? Gary------94 2500 Burb 4x4 6.5 144k Arrest Me Red Mostly stock "6.5 Diesel Turbo" hood decal applied above Surburban name tag on tailgate...(in case those following mistake me for a Gasser)