Mackpro

Power to Pin 85 comes from the VECU Vehicle control unit . The key switch in the start position sends 12 volts to pin A6 of the VECU, then if everything looks good to the VECU it sends 12 volts out pin B28 to the start relay pin 85

Also relay 36 has to be installed correctly or it won’t start. 

Check voltage on both side of fuse 7 with the key on. Dont use a test light. Use an actual meter. The wire coming out of fuse 7 is labeled F7A1. It actually goes out the firewall in the big 100+ pin pass through. It’s pin 68 . Then comes back into the fuse box on the top connector bottom pin

Pin 30 should have 12 volts with key on . This is looking into the fuse box with relay out 

I believe you can still get the original paper engine overhaul manual and engine electric troubleshooting manual for the 2004 emission year MP7 that’s in the CTP/CXP. I still have my copies . A lot of the stuff has gone to digital download on E-media. 

Have the injectors been changed recently? If so, possibly the incorrect ones were installed. Only the first few years of the ETECH style engines had the injector fuel return system in the cylinder heads that went to the fuel pressure regulator via plastic push on fuel return hose. Here in the US the year model range was about 1998.5 to 2001.5 . Then the CCRS and ASET family of engines came out and all used the “leakless” injectors which did not have the plastic fuel return line coming off the cylinder head. A lot of the newer cylinder head casting still had the passage ways in the heads for fuel return system but had pipe plugs in them to block them off. Also the ETECHs with the fuel return in the cylinder heads need 2 O-rings on each injector. The “ leakless “ injectors only need the top O-ring. 

The * is for some kind of “ Limp Home” mode if you have certain transmission fault codes. I’ve never seen it used. 

The fleet shift pad can be replaced with the performance shifter but a software update has to be done by the dealership. The dealership has to request a software change from corporate. After the software is turned on and installed in the truck, there is a parameter in the settings that needs to be changed as well. There are 3 options for this parameter. One is performance mode turned off , one is performance mode on but will return to economy mode after truck reaches a drop in engine load ( up to cruising speed), the last is performance mode on and will stay on till you turn it off on the shift pad or cycle the key switch. On your fleet shift pad if you hit the “M” manual mode button all this does is hold you in the gear you are in. 

The line coming out of the shut off fitting should go to the VGT actuator spin on air filter housing. When you turn off the air via the shut off valve it dumps the air off the VGT filter, control valve and actuator. This lets you change the spin on air filter without draining all the air in the system. There was a Service Campaign or Product Improvement Campaign to add the shutoff and air filter to the early 2003  ASET AC trucks. 

I posted this in another “ Low power after  delete” thread. 

There are 3 of these 64MT450A temp sensors on the AC engine.  The 2-8 code is for the sensor that screws into the intake manifold itself , not the one above it on the angled pipe coming from the aftercooler . If either of the two on the driver side of the engine fail there is a new updated part number 64MT485 that will replace them.  If the compressor discharge temp sensor ( sensor on the pipe between turbo and after cooler passenger side )failed then you have to use the original part number. Mack service bulletin SB273013

The 2-8 code is for the intake manifold temp sensor not the EGR  mass flow and temp assembly 

In loss of oil pressure or low oil pressure the turbocharger seems to suffer first. On the  early ASET AC engines in late 2003 and early 2004 , the turbo and EGR valve shared an oil supply line from the oil filter stand. An update recall had us run a dedicated oil line from the bottom RH side of the engine block to the EGR valve. And the turbo got a new oil supply line as well. If yours was not updated to the new design, the turbo and EGR valve were fighting for oil supply for sure . 

The CH/CHU/PI  are really popular around here and in the used market bring $10,000 or more over the CXU/Anthem trucks with similar miles and specs. Tyson was still buying PI’s up until this last batch of trucks which are Volvo VHD’s. 

Dealership guys told me a couple months back that the D11/MP7 was on the way out and getting replaced by a new Cummins 10 liter. The. MP8 or now know as MP13 has been bumped to 515 HP. Also told this just a few days ago that the PI and GR are staying the same for about a year and a half then they are merging the PI and GR into one truck with lots of frame and suspension and axle options. 

On 6/18/2025 at 2:48 PM, Jody Scott said:

You could try and do what I did and put oversized injectors in and have a MACK DEALER change the program to a 410hp. 

Yes, those split HP programming in the 355/380 and 380/410 did some crazy EUP manipulation to get good power with small CC injectors. Swap in the 460 injectors and you can get great power gains . 

Could be steering angle sensor needs to be recalibrated. If the steering wheel is off center it needs to be straighten and recalibrated using Bendix software. Or possibly the bed company moved the Yaw sensor on on the frame and now it’s out of calibration as well. 

Back in the day we did this to all  the CXP and CTP truck around here. If the sensor shorts out and tells the ECM the exhaust temp is to high it derates the engine. 

On the CXP and CTP only , Mack can’t seem to get an exhaust temp sensor that will last more than 6 months to a year. Their solution is to delete the sensor and gauge and reprogram the dash cluster to delete it so it won’t derate the engine. 

https://www.scribd.com/document/813434003/Mack-AI-Rocker-Bolts-Breaking-Bulletin