Oh boy. Where to start. I bought a 2008 Ford f250 crew cab short bed four-wheel drive automatic with a 1995 12 valve Cummins put in by the previous owner. Long story short before he had the chance to button everything up, he got deported. So I ended up buying the unfinished project from his wife. Needless to say, she didn't know much about the truck and everything that I know about the truck now I have been having to figure out on my own. I can tell that the motor is got at least somewhat of a build because it has studs, an s300 turbo, DPS manifold, and an aftermarket intercooler. Supposedly the truck only needed a power steering pump and because it ran on hydro boost, when I went to take a look at the truck I could not drive it because it had no power steering or brakes. After having it towed home and getting rid of the vacuum pump and the Saginaw pump and converting over to an industrial power steering pump, I took the truck for a test drive and started to realize I had a lot more issues with the truck than I was told about. Which is fine because I anticipated that but I have been trying for over a month to figure out the root cause of the majority of my issues. I'm going to list an order all of the things that I have figured out that do not work with the truck including the DTCs that Forscan is popping up. One of the biggest issues that continue to come across is the u0121 code indicating a loss of CAN bus communication with the ABS module. Here is a list of all of the electronics that are not currently working on the truck

1. No speedometer

2. Dome lights do not come on when any of the doors are opened or the dim light switch is engaged to turn the dome lights on. However I can manually turn on the rear dome lights by pushing the buttons on the lights but that does not apply to the front dome lights.

3. Windshield wipers do not work

4. The driver's side temperature adjuster will not adjust the temp but the passenger side does

5. TCS button stays illuminated in the off position

6. Same thing with the backup sensors button but this one seems to be intermittent as far as the button goes but whether it's on or off, I never get any notification or warning when I'm backing up close to something

So far, I have replaced the power steering pump, batteries with two optima red tops, replace the passenger side body to frame ground that is located behind the front passenger side tire with 2/0 awg copper wire and crimped lugs. I replaced two of the battery terminals on the passenger side. In addition to all this I have also cleaned as many ground wires as I can find. Last night I went ahead and replaced the ABS module computer and after clearing the codes out using torque pro, I turn the truck into the on position and within 30 to 40 seconds u0121 pops right back up. I did insure that all of the numbers on the ABS module computer are matching to mine, ensuring that it's not a mismatch And I disconnected the three large plugs on the driver side by the ABS module and clean them out with electrical parts cleaner before cinching them back together with a pair of pliers and then applying very large zip ties. Thanks to tack helper my tachometer reads, my coolant temperature reads, transmission temperature reads, oil temperature read, I have battery voltage reading, and turbo boost. Short of putting a multimeter onto various pins in the plug that plugs in the ABS module and chasing all of the wiring coming from the plug to the can bus, I'm beginning to run out of options. I hate to say it, but chat GPT has mentioned that it could be the alternator and on the six liter powerstroke that I had, the alternator going bad caused all kinds of weird issues so it wouldn't surprise me. I have read in the forums on here that many people have experienced similar issues with ABS modules not being read due to the alternators being bad. This morning it was 49° f and I noticed that my two brand new red top optima batteries we're giving off reading of 11.9 volts. My truck would not crank without sticking a screwdriver onto the starter. I made it up the interstate to Dunkin and came back out to the truck and it's still will not crank which seems to be an issue when The ambient temperature outside is cold. This however is the first time that putting the key in the on position and sticking the screwdriver onto the two terminals on the starter would not turn the starter over. I stuck the screwdriver between the two large terminals on the starter to turn over the solenoid and then between the small and large post to engage the starter and that was the only way I was able to crank the truck up. I could really use some help as I'm getting to a point where I'm going to have to consider selling the truck if I cannot figure out what is going on with it and I really don't want to even attempt to take it to a dealer or a mechanic around here because I genuinely don't believe that they would know what they were even looking at. The more grounds I have cleaned and established, the less codes tend to pop up. The pictures of the DTCs and for scan that I've listed should be in chronological order. I appreciate any help you guys can give me in advance as I am running out of both time and my wife's patience

 

When you get it running what voltage are you seeing at the batteries? All I have is on Jeeps (chrysler products) the ECM controls the charging voltage not a alt regulator. If the running voltage is to low I wonder if its taking a toll on the other systems. I mean, sheesh..that year Cummins uses a P7100 pump which is all mechanical, so there is no ecm to control the engine best to my recollection after owning a 95 Ram myself.

 

Offhand I'm not sure and I will take a look to see when I head back outside and let you know

 

I would start off by posting and doing some digging in any of the Fummins forums/groups.

See if maybe someone would have a recommendation for a shop that does Fummins conversions close to you if you can't find anything to solve your problems. Bringing an engine swapped vehicle to a regular mechanic would not be my first choice.

From what I have read about 12V conversions you don't need much electronics to get that engine going so maybe you're just not looking in the right place for whatever is causing the issue.

Sorry I'm not any help but hopefully it is something easy you're overlooking. Good luck

 

You've already cleaned most of the grounds. I'd clean or replace the battery cable terminals too, fully charge the batteries and then get the truck running. Check the charging voltage...you'll want to see 12.5-13.8v with the engine running. Modern vehicles toss codes out like candy when the battery is low or the charging voltage is too low.

My '99 had codes that looked like they were growing off a maple tree before I put new batteries in and charged them up. Then all the codes but one went away (exhaust back pressure sensor isn't present...it's supposed to be).

 

I believe these are related. My guess is a pin in a connector is pushed back/ bent/ damaged. I don't have a 6.4 wiring guide on me, but run continuity on the pins between the ECM and ABS module and make sure all the connectors are clean and correctly seating.

This is essentially the same as the 6.0 FICM sync issue on a 6.0 where the FICM has three connectors, the PCM has three connectors, and all it takes is one bent pin or broken plastic tab and the truck bricks itself.

 

How about these issues here's what I've done so far, I went ahead and replaced batters but two brand new red top optimas, replaced all four battery terminals with brand new military style terminals and took the wirings and crimped copper lugs on them. I went ahead and cleaned up the wiring significantly also. Now I have an alternator that will put out 240 amps being built and it will put out an estimated 180 amps at idle. Basically a whole brand new charging system. I don't believe that the carquest alternator is helping anything so I'm eliminating it as an option. Cheap insurance of nothing else

So not to sound like an idiot and I think I know what you mean by running continuity between the pins, but I want to be sure. Is this where you take the multimeter and stick it on one end of something and the other end of where it should come out to? I did take the three plugs on top of the driver side frame, disconnect them with the batteries disconnected for a couple hours already, clean them out with electrical cleaner and allowed it ample time to dry, put them back together and cinched them together with a pair of pliers while I applied a heavy duty zip tie on each connector.

 

Yes, multimeter and run the continuity beep test by touching the right pin in each connector, then flip the dial and ohm the wire. They're called different things (pin probe, back probes, needle probes) but for these connectors use some kind of very skinny probe on the meter and not the chunky Cat III size that they come with by default. Like these:


The pins inside the plugs can back out slightly and not make contact anymore, they can get dirty, bent, corroded, etc. The connectors are notorious for becoming brittle and cracking making the backing-out issue worse. Or could be wires chafing inside a loom, a broken wire, something like that.

Maybe try the 6.4L forum for a wiring guide specific to that PCM so you can know which wires trace where.

 

Amazon link doesn't seem to be working. Something like this lead set, but don't pay more than $10 for a set.

https://www.homedepot.com/p/Ford-Aut...I143/206868625

 

I grabbed a multimeter and compared CAN + to CAN - and got 60 ohms which is to be expected. I figured out that the CAN + wire had been pushed back in the ABS module plug. The tab in the plug is broken that holds the terminal flush with the plug face. That plug is $130 new. So of course I went ahead and headed to the junk yard today and cut off two of those plugs from donors, two just in case I screw one up. Has anyone ever had to disassemble one of these? It's not something I'm comfortable screwing up

 

I just wanted to come back here and show everyone what my issue turned out to be. So you have the three plugs on top of the driver side frame rail. This wire goes from the smallest one of those three to the back of the plug that plugs into the ABS module. In order to do so it has to make an almost 180° turn in the loom. I almost missed it as this was on the back side of that bend