Mackpro

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.

The most common reason the mass flow/temperature sensor assembly fails is failed EGR cooler (cracked leaking coolant internally) or even condensation in the cooler. The sensor assembly can not tolerate any water/liquid and will fail as soon as coolant passes through it. They are very delicate, that’s why they are welded into the tube. The main reason the EGR fails is the screen in the lower radiator “Y” pipe clogs and stop flow of coolant to the EGR cooler and it overheats and cracks .

What settings you needing info on ? Robert Bosch pump I assume?

Engine ecm looks at coolant temp and AC high pressure switch and possibly other sensors to determine if the fan needs to be engaged. Start the engine up cold . A/C off . Rev it to about 1200 and listen for the fan to slow down. Then unplug the Green pressure switch on the AC line by the radiator. The fan clutch should speed up gradually. You should be able to feel the air flow through condenser. We have to pull the after coolers off ours every 2 years to wash the radiators out. A fault code on the oil thermostat solinoid or the piston cooling oil solinoid can cause fan issues as they are on the same power circuit on most truck pre-common rail

On the GR , PI and AN model trucks with the new dash you have to use tech tool. Everything is controlled by the LCM light control module.

The ambient air temp sensor is mounted in the upper right areas of the aftercooler and the AC condenser right below it. When you sitting still and fan clutch not engaged, the heat off the condenser, aftercooler and radiator cause the ambient air temp sensor to read higher than the actual outside air. Once the fan kicks in or you idle the engine up , the fan pulls the actual “cooler” air past the sensor and the readings go down.

Can you figure out what brand steering gear you have ? I have several manuals for the Sheppards and the old TRW /Ross HFB64 and 70 gear boxes. The seal you are locking for they refer it as the sector shaft seals

If you can find out what the actual fault code number was let me know . We only have MP8’s here but had a couple of 2020 year model trucks just randomly loose power and set code for low fuel rail pressure or something to that effect. Ended up the dealership putting 6 new injectors in and it solved the problem.

Looks like it had a variable pump timing set up . The book is from 1997 so I assume this was the time frame .

I have a engine overhaul manual on the E5 somewhere. Back at the dealership, there was a customer wanting to buy 2 RD’s but said our quote was to high and he could get them much cheaper at another dealership. Well he bought 2 new RD’s and brought them to us for low power complaints with in a month. You guessed it E5. We were like “ What the hell is a Midliner engine doing in there “.

First , drive the truck . Even if you repair/replace sensor and clear the code , the code will come back till you drive it and it see a wheel speed reading. Fuse 13 and 14 feed 12 volts to the ABS ECM. Best I remember , Not all trucks need both fuses. Road tractors CHN/CXN have ESP enhanced stability protection that requires both fuses. CV, MR and LE usually don’t have the ESP and don’t need both fuses. The J1939 yellow and green twisted data link wires should have around 2.5 volts plus or minus .5 volts. If you had any power supply problems you would have more than a wheel speed code. If test drive does not clear the code. Jack up the problem tire off the ground. Unplug the sensor and attach a volt meter to the 2 wire harness end of the sensor. Set the the volt meter to AC voltage. Spin the tire and watch meter. The faster you spin the tire the higher the voltage should be. Best I remember 2.5 volts at 50 rpm