My no bus adventures/question

[panzerq]

Hi, long time lurker first time posting. Gotta say have read alot on this site has some good Info.

 

Had a issue the other day with my 2000 24v auto. Drove it around all day fine, parked it in the drive way and changed my brake light switch since the brake lights stopped working. After that they still didn't work so I swapped my multi switch with another one, still nothing. 

Went to fire it up and got a no bus message on the dash, will crank but no start, fuel pump won't prime gauges dont work for volts or fuel level when not running. After messing around checking all the grounds which are tight and clean. Truck has 76k miles on it. Did some more testing, have 5 volts coming from orange wire down at the trans plug.

Found if I put a jumper wire in the asd relay, it will start and run fine no codes. Charging was seeming a little funny after running idling for awhile, cooler here so grid heaters ran for awhile. Was charging at 15 volts and he needle was dancing a little in the cab. 

 

Planning on doing the ground mods, and see if that helps. 

Any other thoughts?  

Thanks

[Dieselfuture]

Some say plug in the back of the cluster can work lose sometimes. I guess make sure all grounds are in good shape do WT mod then there's few connectors by passenger side battery that can lose connection. Check ac noise at alternator to be safe. All the usual stuff that these trucks are vulnerable to. 

[IBMobile]

You're having problems with the PCM.   The PCM grounds terminal 85 of the ASD relay, supplies the info for the fuel and temp gauges, and controls the voltage out put of the alternator.  To start with, check the two ground wires coming out of the PCM for continuity to the right side battery.  They are both black with tan stripe wires in PCM connector C3 pin #31 and #32  You may want to repair all the splices the factory put in those ground wires in conjunction with doing the WT repair.

 

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/electrical/pcm-ground-splice-repair-r675/

[panzerq]

9 minutes ago, IBMobile said:

You're having problems with the PCM.   The PCM grounds terminal 85 of the ASD relay, supplies the info for the fuel and temp gauges, and controls the voltage out put of the alternator.  To start with, check the two ground wires coming out of the PCM for continuity to the right side battery.  They are both black with tan stripe wires in PCM connector C3 pin #31 and #32  You may want to repair all the splices the factory put in those ground wires in conjunction with doing the WT repair.

 

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/electrical/pcm-ground-splice-repair-r675/

Just got done with the wt mod, doing the same thing. Was going to do the passenger side tomorrow 

[Mopar1973Man]

Guess what I'm in the same boat. My fuel gauge just quit the other day and I'm got a new sender in the fuel tank. Randomly my volt gauge drops to 8 volt and homes CHECK GAGES light. Fuel gauge just sunk to Empty and stayed. Im feeling it more PCM fault than wiring. Being PCM controls those two gauges.

 

Only difference is my CCD bus is working and displaying the info as the PCM is reporting. The only thing I can think of for mine if the fender connector is corroded pins for the fuel gauge.

Edited March 18, 2021 by Mopar1973Man

[JAG1]

@Mopar1973Man, where is that fender connector if you don't mind me asking?

 

T.I.A.

[Mopar1973Man]

Master connection for everything behind the cab. Located bottom of the front driver side fender on the cab.

[panzerq]

Well sent the pcm to the place in Florida to get it fixed, said charging circuit was bad and fixed it. Had my alternator tested and it's good. Still getting no bus message after plugging pcm in. Tried jumping the asd relay again and it will start and run but pegs the volt meter off now when running. With it jumped and key on the fuel guage will work, volt guage comes up then falls to zero and check gauges light comes on. In the notes from the repair shop they said to replace crank sensor. Guess I'll try that and see what happens. Any other thoughts?  Did ground mods and all that jazz

[Mopar1973Man]

Remember gauge functions are based on CCD network. If the CCD network is having issues then gauges will act weird as well. I would contact the rebuilder and have them revisit the PCM being its the source of the CCD network.