Mackpro

Thoses codes are odd and uncommon. I had no notes in my manual on them.

Sometimes the pictures in the VMAC 3 troubleshooting manual are shown from the wrong end of the connector. Sometimes it’s looking at the front of the connector and sometimes from the rear. Best to check the actual wire number on the wire itself . VJ3-08-0.8

The EPA killed the option of some HP upgrades on some pre 2007 trucks. Mostly on the AI engines in certain years. It wasn’t due to they way the truck was spec’ed , just maxed out their NOX and particulate matter (soot) output for the year on all the vocational trucks they built that year. It happened to several friends of mine back then with their CV’s. I looked your truck up and couldn’t find a torque limit switch on your truck . Usually only saw those on 460’s with 18 speeds .

The engine ECM looks at the coolant temp and intake manifold temp and AC high pressure switch and commands the fan to engage. If you unplug the fan harness connector from the fan the fan should speed up/engage. Coolant thermostat and water pump and radiator clogged externally ( behind after cooler) is the more common over heating problems. Is this a farm use truck?

Mid144 PPID-3 FMI-3 is Starter relay output , voltage above normal or shorted high. Possible cause is short in harness or relay

The small chrome auxiliary starter solenoid/relay that’s bolted to starter is where the magic happens. The small red wire pretty much comes from the key switch and starter relay in the fuse box. The black wire goes back to the engine ecm. These two wires are in a loom together and come off the back of the engine harness and over the top of the transmission. Turn key off and let truck power down . The key on and then to start position. You have one 5 second shot to check the voltage on the red wire . Which should be 12volts. After 5 seconds the VECU kills the starter relay voltage. You have to cycle the key back off to re-test.

The ecm swap should have let it start. Check ground stud that welded to frame behind battery box. Also check the fuseable link ground wire that goes from negative battery to that ground stud. Had weird issues with this wire and stud.

Here’s the bulletin on ride height setting. Covers all but the Mack “Y” ride suspension. Read it carefully and match up what suspension that you have. Also does the truck have a sleeper? https://pdf4pro.com/cdn/service-bulletin-mckenzie-tank-lines-7fe6.pdf

Power comes through firewall on the second connector down , pic C. This is the back of the fuse box . Then it comes through a 16 pin connector up by the foot valve/wiper motor.

The engine ecm controls the ground for the small auxiliary starter solenoid that on the starter. The engine ecm has the final say on whether to start or not by completing the ground. Using a test ecm and if you can now see engine hours then most of the time you have a failed engine ecm. The test ecm could be from a automatic trans truck or be programmed totally different than the original so sometimes they won’t start. I have see a few times that the power and ground were weak to the engine ecm. It might show 12 volts and ground but under a load there is not enough voltage or ground to carry the load .

With all MP engines that won’t crank . First check engine hours in the dash cluster . Usually under Trip Info. If no hours are shown and only hash marks, check the bottom connector on the engine Ecm for power and ground.

Use good DEF fluid ( not out a jug ), keep valves , and injectiors and engine brake plungers adjusted, get DPF filter and cat cleaned every 2 years. Keep EGR differential sensor ports clean. Have dealership check truck for software updates in the engine and after treatment ECM,s. Make sure both nox sensors and the newest part numbers and not counterfeit if they have been replaced. No boost pressure leaks anywhere at all . Newest EGR differential pressure sensor and venture pipe installed . Boost /temp sensor clean and not soot caked. I could keep going for ever but in reality, everything has to be perfectly maintained and operating for the system to be trouble free.

Sometimes there is a sleeper fan switch on the dash or overhead console. This is where the driver can turn the sleeper blower motor on or off while driving. If it’s switched off I believe the rear controls won’t work.

There is only a intake temp sensor ( 2 wires) on the VMAC 1 and VMAC 2 engines. A boost sensor would have 3 wires . The TEM sensor timing event sensor in the side of the pump. Make sure it’s gently screwed in till it bottoms out and gently tighten the jam nut. Lots of people either back the sensor out a half turn or crank down on the jam nut with a 2 foot long wrench and stretch the sensor and ruin it. Also the RPM sensor under the starter that goes into the bell housing. If it’s not adjusted correctly it will cause surging and missing at high RPMS . It to can be streched by over tightened jam nut . Mack says back out the rpm sensor one turn but we usually do 3/4 turn . Also a ETECH flywheel will fit on your engine but cause the rpm sensor not to read . Seen that a bunch .

Awesome information!

What Joey said and also here’s the service bulletin on it . https://f01.justanswer.com/HeavyEquipmentTech/08b3b0a9-699e-422a-b834-ba684bc06d37_Mack_fault_9-2.pdf

Thanks for the information.

I believe that year they look for the parking brake signal from the parking brake switch above the throttle pedal. Is the parking brake light on in the dash when your air brake buttons are pulled out?

If your having the same issue with both VECU then probably a wiring issue. If you have a ABS ecm next to the VECU, unplug the ABS ecm. Find the yellow and green wires . Using a ohm meter and with key in off position. You should have 60 ohms across the 2 wires. With the key on you should 2.5 or more volts on the yellow wire to ground. On the green wire you should have 2.5 volts or less. The green is the low side and the yellow is the high side . The more data that’s being transmitted the higher the high side voltage goes and the lower the low side goes.

On the Mack sleeper HVAC. Coolant flows through the heater core all the time . There is a blend door that moves to block off the heater core or the AC evaporator depending on if you got the sleeper control panel on hot or cold or somewhere in between. The sleeper AC evaporator has its own expansion valve and runs off the regular AC system of the truck. The actuator sits on top of the unit and you should be able to see it move when you go from hot to cold. I have seen some northern speced trucks that only had a heater in the sleeper.

If you are getting either of the codes I have circled, very possible camshaft lobe on one of the pumping injectors has slipped. We had 2 in one week throw these codes and the #4 injector cam lobe had slipped on both trucks. One was a 18 CXU with 600,000 miles and the other was a much newer Anthem with 300,000 miles.

Proper pump timing is crucial for best performance. Using a Kent Moore A-B light , set the pump timing 1 degree higher than what the tag on the valve cover . Never more than 1.5 degrees or overheating will probably happen. We rarely ever messed with the pump . Good injectors, turbo, valves adjusted correctly, throttle linkage and kill cable adjusted correctly and the pump timing bumped up usually made a big improvement in power.

Here a pretty good video if you got time to kill. The John Deer pumps were pretty close to the Mack pumps

It would be a Robert Bosch pump of that era. The easiest way to tell is where you screw your injector line on. The Robert Bosch pump has a extremely fine spline barrel nut that takes a special socket to remove the barrel and replace pump washers. The American Bosch pump was way more low profile where the injector lines screwed on. The fine tuning of the pumps were not done at the dealerships. This was a pump shop type of repair/adjustment. However like some people said I remember removing the top cover marking the position of the sliding rail with a punch and moving it forward and test driving. I’ll see if I have any information on it in my old manuals at work

http://www.engineprofessional.com/TB/TB011816-1.pdf Info on the screen.