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Code 35 - Over 1,500 RPM (Throw a guess at me..)

Veg_Out

Veg_Out

Walking J Designs
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Boise, Idaho
OK Folks, your opinions, guesses and discussion is welcomed.

My Suburban runs wonderfully. No missing, good starting, no fluid loss etc.

Heath PMD, 1.5 year old IP. Has run veggy and biodiesel too. Now only running diesel.

The old girl throws a "Service Engine Soon" code 35 when the revs hit 1,500 and the light goes out below 1500. Interestingly enough, it won't code during the first minute of operation in the morning.

I've installed a clear line to the IP to see if I'm getting any air in the system, but have no leaks. Considering blowing out the tank sock, but I've got excellent fuel pressure and flow.

Your wild guesses welcomed. Going to throw in a bit of 30 wt. next.
 
What resistor are you running? :rof:

Take a look at this.

36 - Fuel solenoid response time too short.

Defective PMD
Defective encoder sensor
Damaged cal resistor or pins in PMD connector
 
The IP is on it's way out most likely. I just worked on someones truck with the same symptom. He has been running a steady diet of double dose PS and 2 stroke oil. He said it actually got a little better. I did a thread a few months ago on it and IIRC Buddy went into the reasons why it throws that code but it's the armature dragging. The fact that you ran WVO through it would lead me to believe IP damage.
 
Code 35 will cause the cruise not to work. Any stored engine codes and no cruise. A PMD is possible I suppose and if you can get another one to try it's worth a shot but I'd bet IP damage.
 
Don't miss the "wiring" or optical sensor "drop out". If you feel brave enough to change that after triple checking the wires.
 
Will it do this at idle when you rev and hold it over 1500rpm? Or only under load?

Maybe a weak PMD signal to the Fuel Solenoid. The voltage output of the PMD increases with RPM. So at idle you could read the output with a meter as like 2VAC, but it will go up to like 5VAC at 4000rpm. So you could put a meter on the line there and see if voltage progresses up from idle or if it is even weak at idle.

Maybe low voltage coming from alternator, check ignition voltage to the PMD at idle.

Also check the ohms through the fuel solenoid of the IP, it should only be about 0.4 ohms. If its more then internals could be bad. Here is a thread with useful info about checking these things. http://www.thetruckstop.us/forum/showthread.php?23904-jump-A-B-13-not-12-Poppet-Valve-IP-Question
 
I suggest checking idle battery voltage, and voltage across the fuse that supplies the PMD and tapping into the PMD output of pin B to the FS to see that its got a strong enough signal, at least 1.6VAC at idle to any engine ground, then record what it is at 1000rpm, 2000rpm and 3000rpm. And check the FS resistance across PMD harness pins B and F, want about 0.4 ohms.
 
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