Electrical problems

[mbpoindexter]

Since I do not know what modules you actually have I just picked what I thought were logical for an average truck and calculate 909 ohms. The more modules you have the lower the resistance, the fewer modules the greater the resistance.
Here is what I used.
1/3,300+1/10,800+1/10,800+1/10,800+1/10,800+1/3,300+1/10,800+1/10,800. That gives .0011

Then 1/.0011= 909 Ohms

Your truck will be different. In the above example if we have one less module with 10,800 ohms the total resistance would be 952 ohms.

Right,

When I'm doing is going to FSM and just using ctrl+F for D25. All modules with pinouts that contain that D25 I am planning to disconnect

 

[jjdiesel]

Hard to follow all of this but that's a lot of help being administered by members on an electrical dioagnosis.

Nice job to the contributors and good luck to the OP.

Agreed!

 

[mbpoindexter]

Hard to follow all of this but that's a lot of help being administered by members on an electrical dioagnosis.

Nice job to the contributors and good luck to the OP.

To get this truck in good functioning condition from its state when I bought it would cost upwards of 15 grand I would bet. From my efforts and help especially on the electrical I've probably saved at least that much.

We're in the home stretch just gotta figure out this BUS and throttle issue.

Thanks again to everyone, especially @sag2

 

[mbpoindexter]

Well, I tried to go through the P2121 code diagnostics through 04 FSM. I verified pedal was dead before. I took batteries off, waited 30 mins and reconnected. Turned key on and pressed pedal down slowly and it returned then turned key off.

Turned key on, wait to start went away, fired and throttle was not working.

So I went through troubleshooting and ended at step 8 which was refer to intermittent condition. The only other code I have is for low voltage which im sure is there because the sensor is unplugged.

So I'm lost because the throttle doesn't work but its concluded that we have an intermittent problem. Which I guess we did before but seems constant now.

Very odd, any input?

 

[mbpoindexter]

I even changed the APPS, still no throttle. Went through teaching protocol, still no throttle.

 

[mbpoindexter]

And I can't get the BUS to go down....

 

[sag2]

OK. try this for the P2121. Also, do you have engine mounted APPS?

Inspect the engine to body ground strap located between the left rear of the cylinder head and the left side of the bulk head for wire harness contact.

Inspect the 14-way connectors at the clutch / transmission bell housing. Check for oil coming from the transfer case vent which may be getting onto the 14-way connectors.

 

[sag2]

Duplicate

 

[sag2]

It is sounding like you may need a scan tool that can read all the data so you can see exactly what the ECM is seeing with everything hooked up.

 

[mbpoindexter]

OK. try this for the P2121. Also, do you have engine mounted APPS?

Inspect the engine to body ground strap located between the left rear of the cylinder head and the left side of the bulk head for wire harness contact.

Inspect the 14-way connectors at the clutch / transmission bell housing. Check for oil coming from the transfer case vent which may be getting onto the 14-way connectors.

SAG!

so happy you are back. I don't see this ground strap at all....

I may have lost it during the rebuild...let me keep looking...

I do have engine mounted APPS.

I found a similar post about the code p2121 from BigIron70 but no picture, do you have a diagram? I think I'm missing that strap because I did find a broken strap but I thought It came from cab of truck to bed to connect grounds there.

Can I just replace is? Connect a ground from block to body? I was planning to do this in the future. Block to body and block to frame grounds

 

[mbpoindexter]

This strap???? I remember it was left over after the rebuild I couldn't figure out where it went :O

 

[sag2]

Just run a ground strap or wire from a clean metal spot on body to block. It may not be it, but cheap and easy.

 

[sag2]

That's the strap. Just use a wire for now, but they use the straps for a reason.

 

[mbpoindexter]

That's the strap. Just use a wire for now, but they use the straps for a reason.

I'll do that now, I have that diagram and have done all steps for P2121 and P2122 which both resulted in refer to intermittent diagnostics.

This is odd because I have 3 APPS sensors....I have tried all. I put them in, teach the computer with key on. Key off. restart....doesn't work.

I also tried to disconnect batteries for 30 minutes, twice, with the APPS that was in there to try and reset it and recalibrate. It didn't work.

I still don't have any throttle response and when I read codes I get P2121, P2122, P2127. The diagnostic steps result in intermittent condition.

 

[mbpoindexter]

Ground didn't change anything. I still can't get throttle to work at all. Its like the not idle switch isn't working. Voltage isn't getting high enough to flip switch or something.

 

[sag2]

You need a scan tool that can show you the sensor data.

 

[mbpoindexter]

You need a scan tool that can show you the sensor data.

I had it running with throttle for about 2 minutes. P2121,P2122, and P2127 never cleared.

Do you have a recommendation for a scan tool?

 

[sag2]

I'm not sure if Alfa OBD will work on a 2004, I suspect not. That does not leave much choice for inexpensive. For the price of a Snap-On or similar tool, you can make a few trips to the dealer to have them use the DRBIII.

 

[Ozymandias]

He needs Autoenginuity for the 04.5, Alfa doesn't work, I proved it on mine.

 

[mbpoindexter]

I have to go back to FL for the next 6-7 months tomorrow so I'll have to come back to the truck again after that.

I went to move the truck out of my father in laws garage where I've been working on it. Its been just idling when i start it for the last 4 days, no throttle response.

Would you believe when I went to move it out of the way to its "storage" place on his property the friggin throttle was working.

I swear the devil is in this truck.