well this morning, after sitting about 20 hours, I turned on key and got NoBus... left key on about maybe a minute (key ON not START) and after showing NoBus, relays clicked and gauges went up indicating it would start, but I just left key on to see what would happen next... about 90 seconds after turning on key, fuel pump relay started buzzing, and I heard other faint noises from engine, so I pulled the fuel relay and I thought I heard several noises maybe coming from the injector bodies as I leaned into the engine??? then it all stopped in a couple of seconds...

anything here that anyone can ID?

So I sat down and started reading FSM again as to what the PCM does at power on...

see first pic

I saw that one of the things monitored was engine temp so I keyed in on that item.

I then read this... see second pic

I said sensor did not have a lock tab, but mine does... see third pic

EDIT I went out and saw I now had a CEL, pulling the code it said Air Intake Temp sensor HIGH...
further investigation reveals that I have pulled the Air Intake sensor and not the Coolant Temp sensor...
IF THE BOOK IS WRONG... then suspect operator error!

Now I am looking for the Coolant temp sensor

rockauto and advance auto both show a non-locking sensor see 4th pic and 5th pic

the temp sensor is right behind the alternator screwed into the engine block, right?

I really am confused about this sensor... I see rockauto also will sell you a connector to hook to the sensor for almost twice the price of the sensor...

 

There are two there. One is a 2-wire one that sends coolant temperature information to the PCM. The second is a 1-wire one that goes to the dash temperature gauge.

 

Two ect sensors on the 5.9l? I can't find but one.


ENGINE COOLANT TEMP SENSOR - 3.9L/5.2L/5.9L
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is used to sense engine coolant temperature. The sensor protrudes into an engine water jacket.
The ECT sensor is a two-wire Negative Thermal Coefficient (NTC) sensor. Meaning, as engine coolant temperature increases, resistance (voltage) in the sensor decreases. As temperature decreases, resistance (voltage) in the sensor increases.


Have you eliminated any of the modules on the buss? I.have no experience with it, but from what I've read, the voltage on the buss is very low. An interesting thing I read was that it should run with only 2 modules connected to it.

4 or 5 is what you need. Pic 3 is the intake air temp plug?

 

waiting for delivery of parts... I am going to replace both of the sensors I mentioned... coolant and air temp sensors... had to take out the alternator to get to the coolant temp sensor... the FSM makes no mention of that in replacement section so it took me awhile and an inspection mirror to find it

yes pic 3 is the air intake temp sensor

I have yet to try and run with modules disconnected... I'm sure I will get there, but hopefully not have to.

You sure are a night owl Friar!

 

That's why you come here looking for help and I come here to give it.

But seriously, the sensor for the gauge (1 wire) is more on the passenger side of the thermostat housing, and the sensor for the PCM (2 wire) is more on the drivers side of the housing.

 

that sensor is behind the alternator which on my 5.2 is on the passenger side just in front of and below the air temp sensor...

 

Mmm, yeah, I wrote it backwards.

 

Some of the single wire sensors are for alarm lights and some are for dial gauges. Be sure to get the correct one or it will obviously operate erratically.
On my van the alternator is well off to the passenger side and the thermostat housing is under the AC compressor. Fun fun fun

 

Found this on another forum:
So after days of cleaning and renewing grounds and repeating such. Replacing cluster harness, Trying known working PCM, CPS, ACM, TCM, etc.. Disconnecting all sensors one at a time. Numerous resistance and voltage checks..

Problem is solved. It was a very intermittent issue and some of the tests seemed to have varying results which made it very hard to track down, but eventually found by probing the CCD bus wires at the Diagnostic Splice Connector found the WHT/BLK wire that runs from the DLC to the cluster had a fluctuating resistance when it should be less that 1 ohm. Found the problem location and spliced in a new wire twisting according to specs and now works fine!


This was a Jeep Cherokee. His diagnostic splice connector is the connecting point for the CCD BUSS wiring. He was working on the "no buss" for quite a while. Whenever he plugged in a module the buss would wake up.

 

Frier... thanks for that information... I may wind up making my own twisted pair wiring and splicing in all of the modules that it goes to. Currently waiting for some sensors that I ordered to go any further. My problem does seem to have some element of heat related... the problem is not there until I run the van, sometimes for 10 min, sometimes for an hour, then takes it's sweet time to go away, usually overnight, but sometimes within minutes. And it seems almost as if I have two problems... start then die, then restart immediately, then finally NoBus and no start and loss of gauges.

I will have to put more study into the wiring schematic between the modules...

thx again for sticking with me on this problem...