My dad has a 2004 Dodge Ram 1500 that came with the 3.7l. It had about 275k on it and the head gasket gave so we decided to plop a hemi in it instead of rebuilding it (I know the truck has 275k on it and he doesnt want a new truck, this is a clean truck, we just redid the whole suspention got a new set of tires and a complete alignment). Seeming we got a hell of a deal on a very clean low mileage hemi with the computer and harness figured we would give it a shot. The issue is the truck was a manual and the hemi is was an auto from a 2500. Everything has went smooth, 1500 5.7 mounts put the engine in. Clutch and flywheel set from a 2500 manual bolted the NV3500 right up. (I know people think they are week but I have seen it done before and he doesnt beat on or race his cars, he just wants to be able to go from point a to point b without having to downshift 2 gears on every hill) Everything plugged right in like it was supposed to. HP Tuners will be used to switch the ECU to manual. The only issue I am having is now is the drive by cable 3.7l to the 5.7l drive by wire hemi. I have done alot of LS swaps before this and those are simple as can be when it comes to an electronic pedal plugged into a cruise control module then into the harness. These hemis are way diffrent. Minus this issue this swap has been easy as can be, its like mopar made it easy so we could swap em. This 3.7l honeslty shouldnt have ever been put in a full size truck.

So in short can anyone tell me what I need to do to get the truck from the pedal to the engine to function. What am I missing, TPS, Harness, ETC. I also have an extra plug that this truck doesnt have on the harness, I know there is an extra ECU plug for the transmission but I also have a extra retangle grey plug, when the other harness from the 3.7l had just one black retangle plug.

Thanks in advance for any help. We have got the engine in the truck, mounted to the transmission, and nearly ready to fire minus the gas pedal.

 

Accelerator Pedal Position Sensor...... Not sure what they look like, but, the harness you installed should already have a plug for it, just need to get one into the truck.

 

Update: I got a TPS box, cable and wiring harness from another truck at the junk yard and took from the harness what I needed, Pined it to my current harness. Now i am having issues. I got the TPS wired in and even drove the truck around fine. Now my issue is I have constant brake lights with the ignition switch on, and if I enable manual transmission in the computer using HP Tuners I have no crank. Any help would be appreciated.

 

With manual enabled, PCM is likely looking for signal from the clutch safety switch. (scanner may tell you the switch state.... maybe)

Brake lights are controlled by the Front Control Module... The brake switch suggests to the instrument cluster that the brake lights should be on..... Is the CHMSL on with ignition as well?

 

CHMSL is not lit and the pedal does not make it light up, I am not 100% sure it worked before though. Did the PCM from the 3.7l not have a clutch signal wire? I dont see an option from HP Tuners to disable it or let it be controlled in another way. alot of the communication settings talk about a CAN bus controlling mostly everything, atleast from the 3.7l Tune, the 5.7l tune was all disabled.

 

CHMSL is powered directly from the brake switch, that's why I wondered.... Did the brake lights work properly before the engine swap??

 

Yes, They worked fine before. Is there a pin on the PCM i can jump for the clutch. I only ask because the engine revs up if i let off the clutch in neutral i assume thats because its thinks its an automatic but who knows. If i could atleast fix the brake light issue i think id be good to drive.

 

Okay, I just confirmed. Swapped in the old 3.7l pcm and the brake lights turned off with the ignition. swapped back and looked at the dash and noticed a symbol looks like a lightning bolt with with 2 opposite facing parentheses.

nvm on that lightning bolt symbol thats the TPS box apparently. It goes away after maybe 10-15 seconds unless I start the engine it goes away instantly

 

I am not seeing a clutch switch...... at least, not in the wiring diagrams for the starting circuit... Which strikes me as odd. Ignition switch provide power to the control circuit for the starter relay, and PCM controls the ground, so, there likely IS a switch.... somewhere....

 

It would make sense, Ill keep looking hopefully I can find something. Ill check today if the manual setting stops the brake lights. I am assuming the auto transmission and harness on a manual is causing the always on brake lights.

Edit: Brake light is not affected by setting the computer to manual mode, still lit when ignition is on. really starting to wonder about the clutch switch input to the pcm

Another Edit: I get no fuel pump when its set to manual mode in the PCM. Now I am starting to wonder. I know the clutch switch doesnt control the fuel pump. What else could it be?