Code 17 only

[Wwildman]

My 6.5 has a code 17 and no other codes it does have an extended crank when at operating temp. List of mods PMD relocated,new injectors, air dog 2, HX40,and cooling upgrade. As a master certified tech in me says the issues could be a bad coolant temp sensor, bad optical sensor, or because the optical sensor has no filter.

[Wwildman]

After following the diagnostic tree I have 5 volts to the circuit and ground. I also have 2-3 volts cranking. The diagnostic tree says bad PCM

[Robyn]

DTC 17 is related to the optical sensor.

Either a bad optic sensor in the IP or possible the adapter harness that connects the IP to the main wiring harness is bad.

[Wwildman]

DTC 17 is related to the optical sensor.

Either a bad optic sensor in the IP or possible the adapter harness that connects the IP to the main wiring harness is bad.

I ran some test per GM Service manual I disconnected the PCM and let it sit for an hour. I reconnected it and did not start the truck merely turn key on and checked for codes got codes 13,17,18,35,36,49,54
With the 54 and the 17 it becomes an internal pcm fault. Also all these code with out the engine running and the grounds cleaned has me leaning to a PCM


Also I just got off the phone with standadyne and there is nor reason to completely rebuild a pump with a bad optical sensor there is no calibration value only to make sure you place it back in same location.

[Wwildman]

Problem solved after a long conversation with standadyne and ohm checking wires. The PCM was the issue it had a bad driver in it

[Robyn]

Glad you got it squared away.

Electrical issues in these things can drive one nuts.

Easy fix to swap in a fresh PCM

[Wwildman]

Glad you got it squared away.

Electrical issues in these things can drive one nuts.

Easy fix to swap in a fresh PCM

Thanks the biggest thing I found to help anyone is clear codes and do a key on engine off test and see if the code comes back right away. Also following the FSM diagnostic flow chart really helps

[Slippery Smitt]

I just had mine pop up with the same the other day and am trying to figure it out. Code 17 & 18 while running, had 17,18,35,36, & 54 in history. Scanner is telling me its set when the pcm misses 8 or more pulses on the cam without an increase and the pcm goes to backup fuel mode. Makes sense to me.

Friday it was cold here (first good frost) truck took forever to start, which sense I did the heads and other stuff, starts better in the cold, weird I thought. Went up our driveway fine, once on the road and shifted (manual) to 2nd, it fell on its face, no power. Turned around (not on road more than 1/8 mile), did not even want to wine up in 1st. Shut it down, started the same, raced for a second or two then idled fine, tried first gear, it stalled. Got a ride to work and ran the scanner that night. Haven't played with it sense as I had to get the heads on the Safari, (what a beach!)

Lose of power indicates to me backup fuel mode, no signal on the cam and the long cranking propably kicks it into backup mode. Question is, would it be the optical sensor and how bad are they to change? I was going to check the wires today. Or does anyone have any other ideas? I replaced the PCM last year while trying to fix another issue and also installed the Kennedy performance chip at that time.

Thanks
Smitty

[Robyn]

"Raced for a second or two"

Air in the fuel system will cause a loss of power and the engine speed up

This would also explain the long hard start too.

High resolution circuit is the optical sensor. DTC 17

Best to have the IP gone through by a reputable stanadyne service shop and or at least checked.

Make sure of all battery connections and grounds. (Rear of intake manif as well as battery grounds at front of engine)
Be sure of 14 volts at main + lug that feeds the chassis.

Ignition switch failing can louse up the entire system as well.

Voltage issues and grounds will drive these units nuts.

COLD WEATHER
Electrons do not like to flow in cold weather nearly as well as a nice balmy 80 F day
Cold combined with poor (Dirty grounds/++) connections as well as a possible ignition switch issue which incidentally feeds very small wires in the harness to the system.

Any anomalies in the system are multiplied by the cold.

[More Power]

Problem solved after a long conversation with standadyne and ohm checking wires. The PCM was the issue it had a bad driver in it

After 20 years and after dealing with many tens of thousands of EFI 6.5 owners, I can count the number of verifiable PCM failures on just a couple fingers. The PCM is so far down the list of possible causes of an engine running problem that it is nearly dead last.

Stanadyne has always maintained that everything in the truck has a higher likelihood of failure than their pump. They have a perspective... They argued for many years that their pump driver module was not a problem, even after we all knew with absolute certainty it was the single-most problematic part on the entire vehicle.

[svcattle]

Glad you got it squared away.

Electrical issues in these things can drive one nuts.

Easy fix to swap in a fresh PCM


Where can one get a ecm ?

[Slippery Smitt]

Well, the beast is up and running again, till the next thing pops up. Ended up being the crank sensor.

Thanks
Smitty