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View Full Version : Electrical Crossroads, Seeking Opinions



JoeX87000031
04-25-2008, 15:14
I have a 94 K3500 6.5L that has been having electrical problems. I wrote about it in a previous thread with a couple other problems wrapped up with it;

I think I may be confronted with multiple problems. I want to blame the ECM but they hardly ever go bad in my experience. To get to the point, she runs rough with white smoke anywhere from 2200 to 3000. Smooth all other RPM. Here's the kicker. It will only run that good with the coolant temperature sensor disconnected. Once you plug that back in it runs very rough and wont start(actually starts and revs for a split second, then immediately quits.) Pulled 9 codes after running it with the sensor back in. 5 for the Throttle Circuit, and 3 for Cylinder Misbalances. Unlpluged the Sensor and reset the codes, only 1 comes up, that being for the coolant temperature sensor. It's got a new Injector pump. I have already changed the fuel filter and have began to closely inspect the wiring harness. I found what I think was the AC compressor clutch cannon Plug all fried and burnt. Maybe that wasted the ECM? I dont know, but I cant find anything wrong with the wires headed to the coolant temp sensor and the sensor ohms good? Computer should only cost me about 300, anyone else ever ran into something like this?

I have now replaced the injectors, and the CKPS. No luck with the missing. I Ohmed the return wire to the ECM, the 5 volt power line from the ECM to several sensors, what I understood to be grounds for the ECM to the body and the batteries. I checked out the grounding straps when I replaced my injectors and they felt fine.

Thats at lot of info to read about and now see. What I am getting at it that I have established that the coolant temp sensor, wires to and from it, and before and after the ECM are good. A computer costs from 108 to 300. Diagnostics run 95 an hour up here in AK. It costs 100 to flash the computer. I am thinking of just replacing the ECM. Let me know what you think, what you would do. Take care.

Warren96
04-25-2008, 17:39
That thick black wire that grounds to the intake manifold on the passenger side needs to come off be cleaned and re-tightend. Very few ECMs need to be replaced. Are you paying someone to do this work for you?

Robyn
04-26-2008, 07:49
Was the IP a "NEW" one or a reman??

If it was a new Stanadyne unit its probably not the IP but if its a reman Im suspect of the IP.

Hows the PMD?? fresh??

Robyn

JoeX87000031
07-25-2008, 23:49
Hey All,

I apologize for waiting so long to reply. To answer your question Robyn, my IP is a different part number #17800076 than that that came with my truck #10225929<orig. It has a superceeded part number so I dont know if it is new or not, but it is as least of a newer design or something. The pump was changed about two years ago and by how clean the pmd is I would guess the pmd along with it. I have changed the ends of the grounds to new ones, the old one was bolted to that little coolant cap with 2 bolts on the passenger cyl head rear. I put it on the rear intake manifold stud like I saw it in some pics.

Its odd, but things seem to be getting better, but not fixed. After I changed the ground a couple days later it idled down from its usual 1100RPM idle for the first time and surprised me. It only did that once like a little teaser or something. I called the dealer and they said there is a different and specific coolant temp sensor for the 6.5 diesel, I vaguely recall the NAPA parts clerk saying that they where all the same so I am going to spend the $50 and get one straight from the dealer this time. It is continually getting better gas mileage and power over time, I just am not sure why, maybe summer fuel.

Thanks to you all for any knowledge you have sent my way. This forum is immeasurably helpful in troubleshooting this truck. If you could measure the resoursefullness of this forum, I guess it would be about 95 $ an hour savings in labor at the dealer for every thing I have fixed so far. Thanks again all. Take care,

p.s. Warren you were right, changed the ECM and got the same problems, its to bad you cant see that shiny $100 box when its installed because I have nothing to show for it:confused: