I meant to say I hope it is the ECT not the timing having jumped.

 

I’m putting things back together after pulling off the timing chain cover to check that the alignment of the crank sprocket, cam sprocket, mark on the harmonic balancer at TDC with the #1 valves closed, and the rotor aligning with #1 mark on the distributer. I did need to rotate the distributer about 1/4 inch to line it up with the rotor. I might finish with that this afternoon.

I checked the voltage at the ECT connector, with the key at the on position. I get 5 volts on one pin and about 10 volts on the other. That doesn’t sound right to me. If the 5 volts is the supply, I would think the signal pin would read less than 5. I saw that the the supply voltage for the ECT comes from the cam sensor/distributor pickup. The manual says the ECT connector can be put on either way.

I looked up the wiring diagram again. The 5 volts is coming from the cam sensor circuit. The 10 volts is the signal to the PCM. There seems to be a problem.

 

Yep, you have a short to voltage on the signal return wire. Gotta be somewhere in the harness, as the sensor itself can't turn 5 volts into 10.

Might unplug it from the PCM, and test again. See what ya got.

 

I tested the sensor ground wire coming out of the PCM and got about 10 volts. I took the engine harness out again. I took all the coverings and electrical tape off the entire harness. I looked at it inch by inch. I found a few connectors that appeared suspicious and replaced them. I traced the sensor signal wires, the two ground wires going into the PCM and the sensor ground wire from one end of the harness to the other. No obvious shorts. I put the harness back together and installed it again. The only connector that still looks bad, but I haven’t replaced, is the vehicle speed sensor. I ordered one but it won’t be here for a couple weeks.

Now all three ground wires at the PCM have zero volts. But I am getting a voltage too high or low code for the TPS (24),
a voltage too high code for the ECT (22), I tapped into the three wires coming out of the TPS. The ground was 0 volts, reference was 5 volts, and the signal was about .85 at idle and went up to about 2.0 when I reved the engine a little. I tapped into TPS signal wire and ground at the PCM connector and got the same voltages I get at the connector. The TPS code disappeared, but now I have an injector code, and the ECT code is still there. I guess I’ll tap into the ECT signal wire and see what it reads at the connector and the PCM.

I read in the manual that the running lights or parking lights share a ground with the sensors. I disconnected the connector for the front lights but it made no difference.

 

I admire your work ethic Flounderguy. I wish I could deal with a harness so easily. My little ram needs to have it gone through and the best I was able to do was the tail section for the lights that happened to come out in one piece with connectors at each end.

 

Well, yesterday, while continuing to chase an electrical problem, the truck started blowing billowing white smoke from the tailpipe, when I started it up. I hadn’t seen any other symptoms of a blown head gasket before, but it was on my list of possibilities. I definitely have a blown right head gasket.

 

Uh, yep.

Haven’t quite figured out if this is a good thing or not.

I have a recurring clunking noise going on in my front end. Been there for years and getting worse. I cannot find it to save my life. Most of the time I wish it would just blow up. Smoke pouring out. Springs flying everywhere. Just rear its ugly head so I know what it is!

 

Bummer but hopefully this is the problem/fix.

 

Well, damn. I took the heads to the machine shop. Both heads were cracked. They got new castings, salvaged what they could from the old heads and I put the heads back in the truck.

The original problem is still there. The engine starts but runs rough, surges, and dies at idle. It is running rich, the plugs are covered in soot. It runs as if one or more cylinders are not firing. No check engine light.

Almost everything on the engine is new, except the bottom of the engine. I haven’t replaced the distributor or the throttle body.

I considering options. I could take it to a shop and see if they can diagnose it. I could take it apart and have the short block rebuilt but I’m not sure that is the problem. The compression on all cylinders is between 160 and 165. I could get a new engine. I could buy another truck and let this one sit until I feel like working on it again. I need to spend some time pondering.

 

Here’s how it sounds. It gets worse as it runs. Hum the video didn’t attach.