View Full Version : ECM Diagnosis
Back in December, I replaced the heads, replaced parts and cleaned up my old 6.5. The heads I put on needed to be shaved .014" so when I put her back together I used head gaskets .010" thicker than standard. I still had a slightly higher compression so this lead me to:
1) Get the boost back under control of the ecm.
I ended up replacing the wastegate selenoid and the ecm which solved the boost problem.
after several days, she started sputtering and I got the following codes:
DTC 17 High Resolution Circuit Fault
DTC 18 Pump Cam Reference Pulse Error
DTC 35 Injection Pulse Width Error (Response Time Short)
Soo, I look at alldata and follow the diagnostic charts and I either had shorts, open circuits, faulty sensors or a faulty ECM. Seeing as I had just replaced the ECM, I put the old one back in and so far everything is back to normal but the boost does not work again.
Is there a specific ECM that was made for just the 'VIN F' engine or did I get a bum replacement ECM?
Also, I did do TDC relearns every time I changed the ECM with a tech 1.
THis is starting to drive me nuts.
And should I be saying PCM instead of ECM?
Kevin
First -what kind of fuel are you using?
Second - there are several PCM's for the "S", several more for the "F", and two distinct Inj Pumps for the "F", which require specific PCM's to match.
Look on the Stanadyne model number tag on the rear of the IP, facing the intake manifold - post the color, and the DS4-xxx-xxxx number from that tag.
Also, is there a small green tag fastened to the top of the IP?
1) I'm using regular old #2, treated.
2) I replaced the pump and injectors about 15 months ago with one from Kennedy Diesel pump #5521.
When I did my engine redo, I carefully stored each injector in a clean and dry place away from where I was working.
And the prom code is BPRT-BPBT-1621-7113
THe PROM is blue.
No little green tag on the top of the pump.
Kevin PCM PCM PCM PCM PCM PCM PCM PCM PCM PCM
Yeah- I went back thru your posts and saw that 5521........never mind.
Pull the small cover off the Powertrain Control Module, look down in, toward the pink connector, you'll see a small square chip past the EPROM.
Post the numbers off that chip on both your PCM's
BTW - ECM is Engine Control Module - used on gassers.........gassers, patoooie ! ! !
I can go back and edit my posts and change them to pcm...
My wife now tells me my truck is a woman - I'm spending more time with her - and she's high maintenance.
I'll dig the number out tonight when I get back from work.
Kevin
billschall
03-09-2007, 11:07
My wife now tells me my truck is a woman - I'm spending more time with her - and she's high maintenance.
My better half asked me if I had named my truck. I said no, and she said that given all the time I spent last couple of months with it I should call it "Mistress"
mmmm....kinda like it, might stick...
Post the numbers off that chip on both your PCM's
There are two chips directly next to the prom ... the square chip closest to the side of the module on the original PCM is:
185
1610988
d84g
kqevs9347c
the new PCM is:
185
16180988
d84g
kqegg9350e
PCM PCM PCM :D
Kevin
I'm going to get it right!
Ok - with the connectors facing away from you, the chip in question is directly between the EPROM and the connectors
That is the prom, specific to the different powertrain configurations - has the Backup Mode stuff in it.
The other chips are the same for all 6.5 PCM's.
Date code for the first one is 9347, the second is 9350
Ok,
Lets try this (I know its a little big...)
Which chip am I checking??? This is the original PCM
http://www.kkissman.com/pcm1.jpg
Way cool, dude - show and tell rules!
It's the one just above the EPROM - 16156598 with a checksum of C94R
That's for an "F" with 4L80E
If your other one is same, you can use either EPROM in both PCM's for further testing.
the new one is
185
16156589
c94r
kqevc9347h
I'm guessing the last line would be the date code?
Kevin
An english ... how come the spell checker says 'english' is misspelled? ...
Anyway an english professor once said life goes from simple to complex... reversing this for problem solving says lets look at the simple things -
When these PCM's are rebuilt - do they do anything like cleaning the terminals? I'm going to DE-OXIT the terminals of the new PCM and see if that helps.
Kevin
Well I cleaned the connectors on the new PCM, reinstalled it and now I am getting:
DTC 17 High Resolution Circuit Fault
Faulty connector, fuel temperature sensor or pcm
DTC 18 Pump Cam Reference Pulse Error
Faulty connector, fuel temperature sensor or pcm
DTC 35 Injection Pulse Width Error (Response Time Short)
Faulty/open circuit, bad IP pump, or pcm
But the boost works wonderfully. I can hear the turbo whistle.
I do add 2 cycle oil to my fuel - does anyone think this could affecting the optical sensor and throwing off a new working PCM?
Kevin
Maybe English wants a capital E........
GM sells a pink jelly for automotive computer connections - Corvettes and Caddy's have that stuff in the connectors.
Is that really 16156589, or is it 16156598?
That could make a big difference in application, tho the checksum is C94R.
How did that R get in there? It's 0123456789ABCDEF, last time I checked.
Correct - the four numbers in the last line are the date code for that chip - 47th week of 1993.
Find the chip with the latest date code - the PCM was manufactured sometime after that date.
If the latest is years later than the rest, it was installed during some repair procedure.
That's the same DTC's you started with, so OS may be dirty or bad - but, yeah, dirty fuel can cause those codes
Try removing the OS filter, direct-connect the OS , start it again, see if the codes go away.
I removed the OS filter about 6 months ago.
Kevin
The 5521 shouldn't require it, anyway.
Check the 6 wires in the OS harness connectors for frayed, loose, broke, etc - bad connection gives same symptom as bad sensor.
Be sure and check all the engine harness connectors back between the engine and the firewall, and the harness down by the lower ac evporator pipe.
I replaced the wiring harness extension when I working on the engine in December - The connectors on the harness are all fresh and new. I have not checked back by the firewall - That'll be the next thing to do in my free time.
On Sunday night I reinstalled the optical filter and had no problems driving 100 miles (round trip, expressway). I got a car wash last night on the way home - about a mile away.
This morning, I took off and drove two miles away and stopped the engine. Then I drove 30 miles away on the express way and got the codes twice on the way up. I drove home and got a code about a 1/2 mile from home.
Why would installing the optical filter reduce this problem - when I was running without the optical filter - I would get the codes right away and they would not go away.
And if I put the old PCM back on, no codes but no turbo - could the old PCM be damaged in a way that it just runs?
Kevin
Install the OS filter, if the truck is erratic without it - Bill Heath has new filters.
Use the Tech1 to monitor Des\Meas timing, fuel rate, injection pulse width, ECT, IAT, crank pulses missed, cam pulses missed, hi-res pulses missed, wastegate duty cycle, etc, while running with each PCM - look for some parameter(s) that is different.
Get someone else to drive while you look at the data points, write them down for comparison.
In fact, just start at the top of the displayed list and go to the bottom of the list - somewhere in there is the PCM checksum, so verify that.
Comparing data in the list may tell you where else to look, or you can post it here
I decided before I drive myself nuts tracking gremlins in the PCM and electrcial system, I wanted to eliminate the obvious - I wanted to make sure I had fuel that was clean and clear going to to injector pump - soo - I took a clear plastic host and put it on the return line and I have bubbles in the line - I let it idle for about 5 minutes and the bubbles would come and go but, they were definitely there which means...
I have a leak in the fuel line before the lift pump?
is there a common place that gets a leak?
Any idea of a simple way of finding a leak?
Kevin
Remembering that fuel is denser than air, anywhere between the tank and the lift pump - between the lift pump and the filter and the Inj Pump you should see wet fuel signs.
Or, the lift pump could be falling down, not keeping up with demand, so the transfer pump in the IP is pulling fuel from the tank.
So if I open the valve in the front of the engine that removes the water from the fuel filter - that would mean the lift pump is working and I should concentrate on looking for the leak before the lift pump?
Kevin
Yes - no fuel out the drain while engine is idling means the lift pump or\and supply circuit is failed, or the drain is stopped up - make sure the hose-end is clear.
harder316
03-15-2007, 12:39
Just had a pcm put in my suburban had to have it programed at a dealership before she would run. Don't know if this helps. Only cost $70 canadian.
Welcome to the 'Page, tempered stainless............
That was most likely the timing setup - TIMESET and TDCO OFFSET LEARN.
That's a must for any new PCM, and most replacement PCM's - PCM must 'learn' your truck's particulars
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