Catdaddy1958

I get that- but there are no active ECU codes. Is the travel adjustable, like the clutch actuator rods were on some older manuals? I bet that would restore the truck to service. I've seen a picture of the air cylinder- looks like an air operated version of the Mazda/Ford tranny mounted slave cylinder.

Thought I ought to throw this out there- this transmission was replaced by the PO last year. Calibration was not done, vehicle has been in service one year since the tranny was replaced with a 2015 unit. Just found this out. This truck belongs to a friend I'm helping get a business off the ground. I own a Freightliner with a Detroit- much fewer issues with repairs and information... But I learned to drive a truck when there was more than ONE stick on the floor...

Do you know what data the ECU is seeing that makes it disable the throttle? If I stab the throttle, it raises the RPMs ever so slightly and you feel the clutch begin engagement. I do NOT believe this is a mechanical issue- unless it is the wear (reported by SOME sensor) has exceeded the limits- when it worked, it worked fine, shifting, pulling etc. Then it just disables the throttle, and reports FMI 1- data exceeds limits- but WHAT data? I'm considering an aftermarket or even dealer level scantool package to dig into this. It's just wrong to junk a truck because it has an issue that SHOULD be repairable.

That was indeed a great video, and I have been studying this setup trying to figure out the issue. (Just FYI- I got my Advanced Engine Performance Tech rating in 1982- I have been doing electronic diagnostics for decades) INFO is scarce on Mack. What I have yet to ascertain is what the ECU uses to determine wear at either the clutch or transmission brake. It seems likely to me that the ECU disables the throttle because a sensor value is too high (FMI 1), but that doesn't necessarily indicate mechanical failure, When this happened the first time, I drove it another 3 hours OTR and swapped trailers before it happened again. I can't prove it, but the bump engaging the trailer seems to have moved something and caused it to reoccur...

A little update- finally got someone to scan truck- who professes NO Mack experience. No help. No active ECU or VECU codes, but trans codes are: MID 130, PID 36- clutch wear status, and PSID 28- transmission brake. FMI 1. When this first started, it was intermittent, and the truck would eventually work and drove normally. (Weird, but MOVING the truck in neutral to clear the trailer made it work the first two times.) Is there an adjustment to correct this? Or a failing wear sensor? MACK won't work on it because of previous aftermarket repairs to the DEF system, and no one around PODUNK here seems to know anything about them.

Hi guys- new here. I drive a 2012 Pinnacle with M-drive, hauling mail. About a week ago it began failing to move, no throttle response, especially after hooking a trailer. Got it going a few times, but eventually had to tow it 3 hours home. It revs in neutral, but throttle response is disabled when R or D is selected. If you stab the throttle, it will raise the RPMs VERY slightly and fall back. Not enough to move the truck. NO fault codes on dash, gear indicator shows gear selection. I have ordered the cable to connect to my scanner- this is apparently the last year NOT equipped with a standard OBD2 jack- but I hope to get some insight here while I'm waiting. It started as intermittent, but is now completely inop. I did run my fingers over the harnesses that cross the frame. There was a similar post a while back, but no definitive fix or answer. TIA for all help- I'm retirement age, helping a friend get his new company off the ground.