Me and my dog survived the pit bull attack and the vision in my right eye is clearing up, so I want to get back on my shuttle bus tranny issue - P0591 Intermittent Shaft Sensor code with slippage. Mark K has advised me to ohm out the wiring first, before I replace the sensor. I hate bothering him too much and hoped the general crowd here could tell me how to do that. I asked this in my last thread, but never got an answer, so I thought I'd try again with a new thread.

I see the connector (I think) from the driver's side about in the middle on top of the tranny. It looks like I can disconnect it easy enough to have access to the pins. Don't I need access to the other ends of those wires to ohm it out (I'm an idiot about electrical issues)? If so, where are they? I'm guessing it's one of the three big PCM connectors on the firewall in this Eseries. If so, which one?

And I figure I need an ohm meter? Am I essentially sending a charge through each wire from one end and seeing if it arrives at the other? Does that require two ohm meters? Or am I leaving the PCM connector in place and turning on the key or starting the engine to see if a charge comes through each wire?

Not sure why the wire would be bad, but it makes sense to eliminate that possibility first. If it's fine, I guess the next step is to swap in a good sensor? I have my ambulance here and the tranny was working just fine before I did that oil cooler swap (next project). If the wiring doesn't check out, and it's an easy swap, I'd just grab that one to see if it fixes it. Ditto for the sensor if the wiring checks out good. If either of those fix it, depending on what new ones cost, I could go get the ones off my Red Cross ambulance.

Or maybe, it's not worth messing with the ohm meter - maybe it's not much more work to just swap in those known good parts and not take the chance that I screw up the ohm-ing process?

What's a Bonehead to do?

 

Mark K helped with some guidance on my truck, but he doesn't have a wiring diagram to tell me which PCM connector runs to the trans, or how the pins match up. Anyone know where to find those - it's an '06 e450.

 

I won’t talk about dogs, too many painful stories about loosing them. I’ve lived through 9 during my life and we’ve been dog-less for 10 years. The last set was three, mother and two sons.

Ohming the harness is checking continuity of the individual wires, so yes you need the diagram, you need the pin-outs for each connector. You need one Ohmeter, I prefer one that also has continuity, and you may need an extra wire if the leads from the meter are too short.

And as I’m writing this out I’m surprised Sean hasn’t jumped out there with his diagrams or the video of checking wires.

The problem with doing this is you need to be damn sure you’ve selected the correct pins. A number of times I’ve seen people tear apart a harness to do a layover only to find they didn’t have continuity because the were on the wrong pin. Things get real messy after that, not only for the harness but I’ve seen a screwed PCM because the wrong connections. I’ve also watched a guy go completely friggin nuts because he didn’t realize that a ground circuit kept showing a fault to ground because, it’s a ground circuit and connected elsewhere. I’ve got an entertaining radio install story too.

The procedure is simple. Using ohm or continuity on the meter, you check the integrity of the circuit. If there’s no break in the wire, then ohms will be near zero or the continuity checker will sound. Then check if there is a short to ground by taking the far lead to ground. And checking for a short to all the others pins in one connector.

 

Thanks, Jack. Amazing how many scammy-looking websites are pitching wiring diagrams and manuals online. I'm wondering now whether I should even attempt this being so ignorant and not especially lucky when I try to push the envelope on my skills, lol. Or maybe, I might go out of order and swap in the new sensor without knowing whether the wiring is good. I might get lucky and fix it.

 

Mark would have a better understanding of wire issues to part issues as far as failure rates. But I can’t address if that was in his mind at the time of posting vs general troubleshooting. Checking the wiring is second in the diagnostics after getting a code.

Using a meter to troubleshoot is something you should learn based on your modus operandi of vehicle ownership.

Sorry, I don’t have the diagrams for your vehicle.

 

There are a lot of instructional videos out there, I thought this guy was good and sent the link to my grandson. Depending on your tolerance, part of the setting in YT you can speed up a video for voice, I do it often due to my lack of patients.


My wife and I both miss having dogs, I prefer to at least pair them so they have better company then human. Having more than 2 at the same time really brings out a pack hierarchy, which I don't mind. But Les just can't deal with another parting.

 

Gentlemen, I gave everyone a free pass on this one. Continue with discussion of electrical issues and leave the bone laying on the ground.