The Diesel Stop banner
1 - 11 of 11 Posts

·
Registered
Joined
·
1,764 Posts
Discussion Starter · #1 ·
First of all my truck no longer has a 7.3PSD in it.It is now a 98 12V Cummins.The PCM only runs a few things like some of the trans function the rest is through the PCS box.The truck has been running great sense put back on the road in Nov.2011.This issue of blowing fuse has started in the last month,never any issue with this before then.I know the #9 Maxi fuse runs directly to the PCM and PCM relay (they sure this fuse).This is a 20amp maxi.I have removed the #9 maxi from the system and now run two single 20 amp large fuse.One going to the PCM relay and the other to the PCM.Today after 20 miles or so of drive time the truck shut off,the fuel cut on the injection pump is tied into the IDM power source which is controlled by the PCM.I inspected to see which fuse had popped and the one going to the PCM relay had blown.Installed new fuse and blew as soon as I tuned the key to start it up.The PCM relay was hot so I swapped it with another one out the box.Still did the same thing.I am not sure what is causing my issue/s.I know all the relays are the original ones.I have looked into the other systems that the PCM relay controls yet also.I don't know if anyone can help me on this issue just thought I would ask here.Thanks
 

·
Premium Member
Joined
·
9,667 Posts
Here is what that fuse controls as long as you haven't bypassed any of it:

Powertrain Control Module (PCM), PCM Power Relay, Electronic Transmission Control, Injector Pressure Regulator, Injector Driver Module

On other threads where owners have had similar problems it turns out to be in the Electronic Transmission Control unit in the automatic transmission.
 

·
Registered
Joined
·
1,764 Posts
Discussion Starter · #5 · (Edited)
Here is what that fuse controls as long as you haven't bypassed any of it:

Powertrain Control Module (PCM), PCM Power Relay, Electronic Transmission Control, Injector Pressure Regulator, Injector Driver Module

On other threads where owners have had similar problems it turns out to be in the Electronic Transmission Control unit in the automatic transmission.
When you say the "Electronic Transmission Control unit" are you referring to the solenoid pack inside the trans or the gear selector on the outside?While trouble shooting before,I unplugged all the connections to the trans and the fuse still blew.Also,the solenoid pack is new,not refurbished,with maybe 5k on it now.

Testing I just did.I swapped in another power diode and relay from another truck said to be good.Still doing the same thing.
 

·
Registered
Joined
·
1,764 Posts
Discussion Starter · #6 ·
Here is the wires going to the PCM relay as follows:

Yellow from 12v source w/a 20amp fuse

Red goes to Pin 71 (PCM) power input.There is three other coming off this wire.They are Pin 97 (PCM) power input,Red wire into IPR and Yellow/Red out to Pin 83 (PCM) Injector Pressure Regulator and then to IDM relay out to Pin 70 (PCM) IDM Enable Output.

Black ground

Black/Yellow from Power Diode.The Power Diode feeds Red/Light Green wire to Glow Plug Relay out to Purple/Orange wire going to Pin 101 (PCM) Glow Plug Control Output.

I am not using the IDM,IPR or GPR.
 

·
Registered
Joined
·
1,764 Posts
Discussion Starter · #8 ·
The transmission is a E4OD using a PCS (Powertrain Control Solutions) box.It gets power from a 12volt source and as far as I know the only thing the PCM does is control a/c switch and some instrument panel lights.Everything transmission related in the PCM is now done by the PCS.
 

·
Premium Member
Joined
·
9,667 Posts
With what it sounds like you have done to the truck you are going to have to go on a treasure hunt to find the problem, it will be hard for someone that hasn't done the same conversion that you have to try to figure it out.

One thing that I would suggest is that instead of placing 2 20 amp fuses in the circuit as you said that you did, how about placing the original 20 amp with a 20 amp and either a 10 amp or a 15 amp going to what ever you are testing. That way the lower rated fuse will blow before the main will if the problem is in that leg of the circuit.
 

·
Registered
Joined
·
2,374 Posts
I would start by disconnecting the stock PCM, just to see if that keeps from blowing the fuse.

The only dash lights I can think of that the PCM controls are the WTS and the CE lights. Neither of these mean anything on your truck now.

As for the A/C, I don't think the PCM controls the A/C. I think it ony receives a signal from the A/C when you turn it on. IOW, the A/C is an _input_ to the PCM, not an _output_. There MIGHT be an output to interrupt/disable the A/C at wide-open throttle, but presumably you're not using the OEM go-pedal. So you may not need the OEM PCM at all.

So the PCS box is on a separate circuit, and any circuits that previously went between the TRS (switch/sensor on the transmission) and the OEM PCM now go to the PCS? Same thing with the solenoid wiring to the transmission?
 

·
Registered
Joined
·
1,764 Posts
Discussion Starter · #11 ·
Ok fellows here's what I dis yesterday.I tripped the unused wiring from the the factory harness (IDM,PCM and Main to interior/panel).I separated the injection pump fuel shut off,which was connected to the old IDM power wire,to another 12v key on wire.Also,changed where the PCS 12V power was,which was also hooked into IDM power wire(Dark green/Orange strip).So far it is doing good with about 100 miles on it now.For further info,the PCM doesn't control anything other than a few dash lights now.I thank you all for your advice in helping with me with my problem.
 
1 - 11 of 11 Posts
Top