wow thanks alot !! my nephew was here and he is actually going to down load it .. Thanks again for your input and of course the holy grail lol!! seven...

 

Well I have tried about everything so the only thing I can figure out is that their is a break some where in the harness.. communication to the scanner is still a problem so what I was going to do is run a "pair" of wire from the gray plug on the pcm to the obd connector because I believe I am still not getting the proper ground signal their.. I am going to follow the path of the white /bk stripe and the vilet/ brown stripe and see if their is any change ?? don`t know what else to do ,if this doesn`t work gonna sell it as a parts truck.. it is pretty clean has a set of 31 on it and a brush bar lol at the end of my rope , Thanks to all for the input and advice can`t win them all but you can try... 7

 

Maybe you should hold up on jumping wires between the PCM and the DLC.

Here's a schematic and a diagram of the CCD Data Bus DLC and the modules connected to the Bus.

THe DLC is just a portal to the CCD Data Bus and really does have anything to do with "running" the Bus.

If you are having problems with the scanner "Communicating" with the PCM, note on the schematic that the SCI (Serial Communications Interface) pin cavities 6 and 7 at the DLC are the ports for the scanner to communicate with the Bus. These SCI circuits are connected to the PCM, TCM and ABS Module (if you have it). Pin cavities 3 and 11 at the DLC are the CCD Data Bus ports. Pin cavity 16 is used to power the scanner; it gets its power from fuse 17 in the PDC. Pin cavities 4 and 5 are the grounds for the scanner; they terminate at the oil dipstick tube mount stud.

You should make sure the pin cavities on the DLC are not corroded (Gray or Black appearance) and that the pin cavities are not enlarged by someone shoving meter probes in them.

You can check for power at pin cavity 16 using you Voltmeter (+) probe to 16 and the (-) probe to 4 and/or 5. You should see battery voltage.

Edit: The PCM and all modules shown in the schematic must be connected before doing the followin tests.

You can check the heath of your CCD Data Bus by using your Voltmeter (+) probe to pin cavity 3 and (-) probe to 4 or 5, and the ignition switch to ON (RUN), without cranking the engine. You should see around 2.49 volts. Repeat by going from cavity 11 to 4 or 5. You should see around 2.51 volts.

If these voltages are lower than 1.8 volts or higher than 2.8 volts, there's a problem on the BUS.

There is a set of resistors in the PCM that control these voltages. If the voltages are off, check the resistor pack in the PCM by using an Ohmmeter. Disconnect the battery negative cable, touch pin cavity 3 with the meter (+) probe and cavity 11 with the (-) probe. You should see 120 Ohms.

If the resistance is lower than 120 Ohms or the voltages are not within min/max limits, the PCM is bad, a module on the bus is corrupting the Bus, or there is bad wiring somewhere in the CCD Data Bus.

 

Ok I weill give that a try but if I remember right the black and brown stripe wire ground from the pcm I dont think I am getting a ground from that pin # 5?? I know I have power their and at the ground next to it #4 the black with brown stripe #5 I have tried three different computers in their so far all with the same results..?? Thanks Bill

 

If all the tests described in the previous post are okay, continue.

Concernng the ASD relay clicking and the E-Fan running; the relay control coils for these two relays are activated by the PCM providing a ground path for each relay when conditions are met.

You can check the relay control coil circuits to the PCM in the following manner:

All PCM connectors attached and the battery connected.

Remove the Fan relay and the ASD relay.

Refer to the relay socket diagram. You're interested in pin cavity 85.



You are checking to see if the relay control ground circuit wires between the relay (cavity 85) to the PCM are intact.

Using a Voltmeter touch pin cavity 85 with the (+) probe and the (-) probe to battery (-) post or to the chassis.

With the ignition switch OFF (LOCK) you should see between .02 and .150 volts.

Repeat with the ignition switch to ON (RUN), without cranking the engine. You should see approximately the same voltages.

At each check wiggle the wires coming out of the PDC, along the firewall, and at PCM. There should be no change in the voltage readings.

~~~~~~~~~~~~

Check for relay control wires from relay socket pin cavity 85 to the PCM for short to ground:

Refer to the relay socket diagram above and PCM connector C3 pinout below.

Disconnect battery negative cable.

Disconnect PCM connector C3 (Gray).

ASD Relay - Using your Ohmmeter, measure the resistance between ASD relay pin cavity 85 and PCM C3 connector pin cavity C3. You should read near full continuity (no more than 5 Ohms). Wiggle the harnesses to see if the resistance reading changes. Next, read between relay pin cavity 85 to chassis/engine ground. You shuld read infinity on the Ohmmeter. Wiggle the harnesses to see if the reading changes to continuity.

Fan Relay - Repeat tests as in the ASD relay tests above, only probe pin cavity C2 of PCM connector C3.

Note when looking at the PCM connector C3, pin cavities C2 and C3 are side by side. Visually check the harness wiring at the connector for evidence of corrosion and the PCM connector socket for the same.

Using your Ohmmeter (with both relays removed) measure between pin cavities C2 and C3 of the PCM harness connector C3 and see if there is continuity between the two.

 

If I am following your directions properly the first thing I did was to make sure I had 12 volts at pin #16, that was good the second was at pin # 3 + probe pin # 4 or 5- probe volts are0.09?? did it three times to double check.. next pin #3+ to pin #11- check ohms with neg battery cable disconnected from battery only reading 60 ohms?? I have the orig pcm gonna switch it back in and see if the numbers change or the same >// The third pcm is in a working truck can not get to it now.. Looks Lilke either a wire broken or all these pcm are bad?? Bill

 

WOW!! This is sounding like myself right here and the issues that I am having. Well, not exactly but, everything that CCKen has sent you he has sent me. Everything that you are seeing as far as voltage and Ohms is the same thing that I am seeing. When he referred to one the 5 JBs going bad and one of them went for a swim...well mine is the one that went for a swim..

 

When you read .09 volts I'm assuming you had the ignition switch in the ON (RUN) position (?).

If so, it could be a bad Module on the Bus causing this.

But, go ahead and do those other checks I outlined.

 

Sorry got distracted ,anyway no the ign was off.. I rechecked same results.. going to do the rest of the test tom afternoon a buddie is stopping by he has a much better scanner and a fluke meter and a better set of eye`s back, knees ,etc you get the point., lol maybe we are onto something?? it was defitnetly in the off pos key out of ign.. Bill

 

I only wish that was the case with mine ?? I can not see anything obvious.. CCken has sent me some great information though probally would have given up if he wasn`t trying to figure it out...

 

Hey everybody just trying to keep everybody that has been helping/ advice updated with latest finds..Today a friend of mine came over and as CCKEN suggested we started following the ccd bus circuit with basically the same results,. I took his advice and did not jump it out.. The fan turned on like clockwork and a/c relay clicking away as soon as the key was turned to the on position which is what we are really trying to get rid of., anyway out of frustration I started moving any wire I could when I got to the gray plug on the pcm I noticed if I pushed it in real tight against the pcm the fan shut off and no relay`s Clicking ?? I think we might have found the problem as soon as the fan shut off no bus displayed on the cluster, which my buddy believes is the crank sensor, as it will not start.. when the fan shut off by pushing gray plug which is now zip tied to pcm,. it seems like it was before all of this started.. One of the guys that was helping made the mistake of opening the gray plug and we are really haveing a difficult time getting it back into the housing.. ?not sure what to do about that?? Anyway just wanted everybody to know I think we are makeing progress,, and yes we had cleaned and checked that plug before but never really pushed it in tight against the pcm like that.. ?? Pretty sure we are going in the right direction.. at least I hope?? lol, 7

 

Just to update it was not the gray plug now that I have repaired that issue as soon as the key is turned to the on position the fan and asd relay start clicking and fan running almost thought we had something?? And now it is a no start issue also.. I see the punisher is going through what looks like the same thing?? I really hope not I spent a lot of hours and burned a few favors with this issue with neg results .., I think it is time to part it out..

 

You mentioned in your first post that it would start and run, but you had to hold the throttle open to make it run. Have you replace, or swapped out the TPS? Having to hold the throttle open is usually a dead give away that it's bad. It is one of the 5v sensors and if it is shorted you would have the "No Buss", and could possibility cause the coolant temp sender to read wrong (they share the same PCM ground along with the IATS) causing the PCM to think the motor is grossly overheated shutting everything down by dropping the ADS relay.

Also to clarify you are no longer having the A/C issue after repairing the PCM plug right?

All these sensors, and relay control circuits in question are on your grey connector. I would double check your work on it, and do a continuity test on all the wiring associated with the sensors, and relay control circuits on it.

 

Hi thanks for the reply, yes I did try switching the tps sensor same exact response., And when I did repair the gray plug the fan came right back on as soon as key was turned to the on position, along with the asd relay clicking..as it has been doing from the start., Originally it did start and run but the fan would not turn on when it would hit temperture ,only before it would start even with a cold engine now it will not start it will crank but pretty sure I lost spark?? .. I am only guessing the crank pos sensor is bad?/ not sure it was raining here today so didn`t really get to look at it again..Also kind of running out of patience with it ?? So far I have changed the alternator, two pcm`s one tcm, ign switch, tps, iac, pick up in dist., two different clusters and checked every ground, and connector , removed and inspected the jb or fuse box, inspected the pdc box gone through both harness`s , really out of option`s shame it is a pretty clean truck but think I am going to sell it as a parts car do not know what else I can do..

 

There is a ohms reference value to use on the CPS to test it, but I can't remember what it is. However if it's shorted out unplugging it should cure all the other symptoms. It won't start, but all the wankyness should be gone.

How close are you to me? If you do decide to give up on it I might be interested in it it the price it right, and you are close.