After towing a trailer on a really warm day engine would crank but not start until temperature went down. Code U0101, no communication with transmission module. Later that day it would start and was fine for couple of days. But when I hooked up the trailer again, engine died after 30 miles of driving with the same trouble code. It will not start again. Do I need to get my transmission module control replaced/repaired? Did anyone experience this issue before? Last time transmission fluid was replaced at 140k miles.

 

I’ve never had it to where the car wouldn’t start - it would go to limp mode locked in 2nd gear,

it’s possible that you dislodged or created so much grit that the vehicle speed sensor connectors in the valve body are now blocked. This is a typical failure mode and will require a dealer to reprogram the valve body to the new vss. There are also third parties out there that do this.

but first - have the car read out on DAS to confirm the specific error. U0101 is a very generic OBd code.

 

You are correct. I got my DAS working again and the error code is 0513. No communication with a transfer case module. Now I just have to find where its located.

 

Software told me to look there but it is not there.... maybe that is my problem

 

In DAS, go in to both the CDI4 and transmission and post here what the codes *AND* events show for both modules. Also post a screen shot of the control module version info (very top selection) for the transmission.

When it didnt start, did the electric fan begin to run at full speed? U101 is the early sign of a failing NT15/3 transmission control module (not the speed sensors). Please also ensure the connector at the transmission is fully seated.

 

I did check the transmission connector, it looks good. Fan does not run when I try to start it. Transmission has no fault codes but has one stored event: "0513 The CAN signal for start enable sent to the drive authorization system by transmission control is missing or invalid." This sounds like the issue I'm having, something is preventing engine to fire up. It does crank.

 

I also don't hear the fuel pressurizing when I turn the key. I'm sure that is why CDI4 is complaining about low fuel pressure. I should check for fuel delivery. Maybe the trouble codes are little misleading. It seems like immobilizer won't let the engine start. Does anyone have any other suggestions?

 

I checked the fuse and relay for the fuel pump, all good. Plug to the unit gets power. When I apply power directly to the pump, nothing happens. I think that is my issue.

 

Just wanted to post a quick update and solution to this problem. New fuel pump fixed the issue. I was suspecting it was fuel related from the start but I went after CEL codes instead. Don't be like me and do basic troubleshooting first, make sure that you have air, "spark", and fuel. I still don't know why I had those trouble codes.
PS. Fuel pump was running and making little noise but no fuel was coming out, when I tested it.