turckster

Long 3/8" extension, wobble socket, good long handle 3/8" flex head ratchet. You can access it from the bottom. It's not so bad getting the nut off, a little tougher to get it back on. It'll take some patience, maybe a few cuss words.

The ground relay is usually mounted right next to the wiper motor.

Something I've seen many times is the ground relay pop open while cranking preventing the engine from starting. Usually its caused by a bad starter internally shorting out causing the ground relay to open while cranking. You could try a heavy gauge jumper wire and connect the terminals and try to start the engine or try a DVOM to see if the relay is open or opens while cranking.

With the connector secured in the holder with wire ties, if you wiggle the harness does the engine sputter or cut out intermittently? if no then the issue may be inside the injection pump governor housing. If yes, the best thing to do is crimp on new terminals and replace the chassis to inj. pump harness connectors.

If this is on a 1994 CH613 then that turbo does not have a speed sensor. Turbo speed sensor was not introduced until v-mac 3 AC engines. Being a 1994 you will have the v-mac 1 electronics system, the only blink codes that start with 6 are 6-5 (Battery low voltage) and 6-6 (internal module communications).

Something I see sometimes when this happens is the wires at the connector plug start to fray inside the insulation before they end up breaking or the connector housing on the sensor is cracked. The temp sensor is located on the right side of the trans near the 6 hole pto cover. Sometimes debris from the road will kick up and damage the sensor. On v-mac 3, the shut down feature can be turned off.

You should check voltage at the alternator and compare it to voltages at the starter, cab and batteries. There should not be more than .5 volt variance. There is a ground relay next to the wiper motor, make sure the contacts are clean. I would make sure all cable connections are clean, including grounds on the block and frame. The alternator should be putting out approx. 14.1 volts, voltage inside the cab should be around 13.8 volts or so.

If the dash gauges are not working it should not affect engine operations like the engine fan (cooking fan?). If the engine fan is not kicking on then you have other problems. If you have an electronic viscous fan like a Borg-Warner (has a huge aluminum housing), you can unplug the fan, secure the connector, start the engine and within 30 seconds the fan should be fully engaged. If not then the fan is bad. Plus if it looks like oil is leaking around the hub then that is another sign the fan is going or is bad.

The new exhaust adjustment for MP8 engines is adjust the exhaust valve with 1.0 mm or .040", leave the feeler gauge in while checking the engine brake rocker with a 2.5mm shim/feeler gauge. The old adjustment had you remove the 1.0 mm then check the engine brake rocker with the 3.5mm shim/feeler gauge. When I say new I mean it's been that way for quite some time. I guess the engineers feel the newer method is more accurate.

Yes, a round white/grey connector. It has a twist type lock.

A 7-5 fault for vmac ll is the Rack Position sensor (current below normal or open). Most likely the issue is a bad connection at the inj. pump to chassis harness connector. While the engine is running try wiggling the harness and connector to see if the engine stumbles or dies. If so I would check the pins to see if there are signs of arcing or if they are discolored. Sometimes the connector can wiggle lose and cause what you are seeing. Try to secure the connector the best you can using plastic wire ties. If that is not the issue then the problem could be either the harness cord to the pump or inside the electronic side of the inj. pump. If it seems that the engine dying happens only when it is hot it might be a bad solder joint or bad rack position sensor. If that is the case the governor housing will have to come off.

Does this engine have the air purge system for the 7th injector? I have seen the air regulator (mounted behind the air dryer) go bad and send system air pressure through the air purge system and back feed to the fuel system. A bad "T" check valve at the 7th inj. will do that as well.

Usually software updates extend sensor parameters or include enhancements. All the testing in the world means nothing compared to real world application. Because of excessive warranty failures, engineering may realize that extending sensor parameters will prevent further issues. Its kind of a learn as you go thing. Many diagnostic steps require checking for new software updates.

Low idle adjustment can only be made if the option is enabled and the chassis is not equipped with an automatic transmission. If you have an auto or the feature is not enabled it has to be set using Mack software. Plus there can not be any active faults. To adjust the low idle: the vehicle must be stationary and park brake set and the throttle pedal at idle. Turn the speed control switch on/off 3 times within 2 seconds. the idle will drop to 500 rpm. Depress and hold the accelerator pedal until the desired rpm is reached. Depress and release the set switch then release the accelerator pedal. Depress and release the clutch pedal, this speed is now locked into v-mac3 as the new low idle speed

Is the engine harness ok? If the old sensors pushed oil into the harness, has the oil contamination made it to the eecu terminals? If so the oil contamination can cause electrical glitches. The only good cure is a new engine harness. A temporary fix is to clean out the oil contamination with electrical contact cleaner but the oil will migrate back.

Everything looks ok so far. Was it still building temperature? To be honest, I've never really paid attention to the drv status light unless the inlet would not build temp.

I would make sure all fuses are good and check the pins on the connector. Every once in a while I get a connector where a pin pushes back when plugging in. Just enough to make it a problem.

Good catch on that. It's little things like that that will have you pulling hair.

I'd make sure each one of the terminals in the switch connector are clean and have a good amount of drag when sliding a terminal in/out.

The best thing to do is to pull the oil pan, use the primer pump to build pressure. Sounds like a pretty good leak so you should see it easily. One thing to keep in mind though, if fuel is dripping out around the gear train most likely its a bad seal on the transfer pump but it could also be fuel leaking around the lower fuel galley plug under the front cover. Usually a sign of this is wetness right below the upper galley plug--leaking around the front cover. I have seen quite a few that the plug had backed out completely.

Check the EGR diff psi sensor(using ptt2) with the engine not running, should be 0 psi +/-.3 psi. If the egr is flowing, even slightly, it will cause the exhaust temps to cool down. Try following g/d symptom based diagnostics.

I can't remember but I think the primary and secondary air sensors are located in an air manifold right above the throttle pedal. The wiring might be tagged what circuit it belongs to.

Best advice I can give is since you have ptt2, I would follow guided diagnostics for that fault. You have to flow test the nozzle to determine if it is bad but since they are relatively cheap its not a huge loss if that wasn't the problem. The fault with that fmi lists 3 possible causes: 1-fuel line(either kinked or plugged), 2- plugged doser valve , 3: bad aftertreatment hydrocabon dosing module.

Blower Motor Switch Wiring Upgrade.pdf

The speedo sensor is located at the rear of the transmission. Measure the resistance of the sensor. If it is gold in color(old style) it should be between 200-300 ohms, if it is black and looks like plastic(new style) it should be 140-180 ohms. If that is ok, remove the sensor and check the tip for damage, also make sure the tone ring does not turn (use a screw driver through the sensor hole and try to turn). If all looks ok, try reinstalling the sensor and make sure it is adjusted properly. Screw the sensor until it contacts the tone ring, back off 1 turn and lock it down. The gold colored sensor looks like the older style sensor Mack used to use, should be ok.