major code prob w/ detroit

I honestly would ask your mechanic if he has an extra ECM around you can swap out to see if it works. I am almost positive you have a faulty ECM, but the only way to tell is to remove it and replace it and they are not cheap, so finding a used one to TRY would be best.

Since you have already replaced the oil sensor and actually ran the truck with it unplugged but the code still comes up, and the fact it has so many random codes makes me believe this. But again, i have only had 1 Detroit truck, but I did run into the same problem and once I replaced the ECM (cost $1,800 at Inland Detroit) I never had a single problem with the truck again.

 

Check for your 5 volts at the intake manifold sensor, (turbo boost sensor, yes the black module in the intake manifold). That sensor is easier to get to. You will need a digital multimeter. Connect the black or negative lead of the meter to ground and just check all the pins on the sensor connector with the red lead one at a time. The key needs to be on. With the sensor unplugged you will cause a Check Engine Light, no worries. When you test for power be very very careful not to bend or damage any of the terminal inside the connector. Do not cram or shove the meter probe inside because you will spread the terminal apart and it won't contact the sensor lead when you plug it back in. One of those terminals will be your 5 volt. You should see something pretty close to 5 there.

 

If you can find a loan ECM you can hook it up to try. Any S60 ECM that looks the same as the one you have will be ok to test run for a short time. An 11L engine will idle and free rev on a 14L ECM etc, but I wouldn't advise you try to drive the truck. You will probably get codes logged if it has different options to yours.

The turbo boost sensor is the flat black plastic sensor bolted to the inlet manifold with two screws. Disconnect the plug and probe the front of the terminals for 5v with the key on. Be careful not to spread the terminals, or you will create more problems. Get two short pieces of auto cable and bare back the ends to expose the copper wires. Cut most of the copper strands back on one end of each wire leaving a few strands that can be inserted into the terminal. Connect the other end of the wires to your multimeter. Doing it this way removes the risk of spreading the terminals.

You need to check for 5v at the sensor terminals as both supply(positive) and return(negative) go back to the ECM. Checking for 5v to chassis tests the supply, but not the return.

The return wire has a join inside the Engine Sensor Harness. From memory this join is somewhere near the rear of the starter. You will need to open up the loom to find it. I have had a couple of looms with this problem, that had faults similar to you.

 

You posted while I was writing reply to your previous post.

Rotary switch to DCV 20.
Black lead into COM, A of connector.
Red lead into VnmA, C of connector.

If I have A and C reversed the meter will just read -5.00volts, instead of 5.00 volts

 

I think you have fixed your problem. Over temp of oil will derate the engine and show a check engine light. I would try a load before spending any more money.

I wish I had never sold my '95 IH 9200 with an 11.1 in it.