Engine/Transmission (1994 - 1998) Hot problem

[Balzac]

I have had trouble with my 95 for some time. When weather is hot, I stop for a few minutes, then when I start again, there is no tach, no alternater charge, no O/D, and no cruise. This tells me that the computer thinks the engine is not running. I first replaced the Crankshaft sensor, still the same problem. Last week when I drove, same happened, but also the check engine lite flickered, and the tach was erratic. I have tried to check the wiring, but could not find a problem.

Any ideas?

 

[Balzac]

Today I cleaned the ECM ground, put in a new Cummins crank speed sensor & now no tach,alternator, OD, or CC when cold or hot.

 

[GAmes]

Today I cleaned the ECM ground, put in a new Cummins crank speed sensor & now no tach,alternator, OD, or CC when cold or hot.

Did you set the gap with a non-magnetic gauge? . 049-. 051 inch

 

[Balzac]

Thanks, yes I did

 

[GAmes]

I hope you have a factory service manual. You need to check all the ess wires for continuity from the sensor all the way to the pcm. It doesn't happen often, but every now and then the wires break inside the bundle. I had that happen to my tail light circuit. Rather than ripping all the tape off the harness to repair the break, I just strung some new wire. But before you do that, just in case, there are two grounding wires just forward of the air horn on top of the engine. There is another near the thermostat housing. One of them might be the ess ground, I don't know.

 

[Missouri Mule]

Engine Speed Sensor (Crank Sensor):

5 volt supply= Violet/white wire

Signal =grey/black

ground =black/light blue

Ground 119/112 on top/front intake manifold or head for PCM.



Usually if the ground is bad for ESS the A/C will not work( that's no tach/volt/od/a/c) never read where the ESS will cause cruise to malfunction.

 

[Missouri Mule]

Looking at the Electrical Diagrams A4 On the PCM supplies a ground to the Engine Speed Sensor and the Cruise Control switches on the steering wheel( and on other sensors).



A31 and A32 on PCM (black and tan wire) go to ground 119

 

[Balzac]

I checked the connector above the ESS, unpluged, checked the 3 pins going to the ECM. Could not tell the wire colors but while looking at the pin holes, flat bar at bottom, right ground, top 9volts, left 5volts all with the motor running. I believe this indicates the wires are OK ?

I am thinking the ECM, I see refurbished at Autozone for $199 to $265, could also try the Wrecking yards for used. Could also borrow a friends, same model, and try that. Any suggestions? I still haven't tried checking the wires for continuity.

Also remembering the problem was caused by heat, but after installing the new Cummins ESS now does not work cold. A year ago I tried a new ESS from Chryco and it also did the same as now, no work, so I returned it to Chryco and told them it was faulty.

 

[GAmes]

I would try swapping the PCM with your friend's. I hate throwing parts at a problem.

 

[surfbeetle]

Computers don't like heat, so it could be coincidental that it has failed about the same time you have changed out the sensor. If he's up to it, I would also suggest borrowing your friends ecu. If you put your ecu into his truck and it does the same thing, you know what the issue is and if your truck does well with his ecu, you also will know. I would only be afraid of putting his ecu into your truck and there be some shorted sensor or wire that could mess up his ecu. I'm not speaking from automotive experience on that, but rather as an IT computer technician.

 

[GAmes]

Just to nit-pick, '95s do not have ECMs or ECUs. They have powertrain control modules (PCM). There is enough confusion in the troubleshooting world. Using the correct terms decreases that confusion a little.

 

[Balzac]

I had my PCM refurbished, then still no tach etc. , then replaced the new CSS from Genos, ( Cummins part ) with the old one, now everything except the CC works!