Back into hydraulics a little bit... Allison Automatic valve body and Ford IPR valve

What I've got from digging into these is that they are really not very complicated. All that makes that Allison (3060 I believe?) work are 6 solenoids and 4 ports. Clutch packs etc are the same as any other automatic and are somewhat familiar as I've been in a Ford AOD before.

Week: 40

FQ2013

More on the Cummins M11... Performed starting charging test and got 10.43 cranking volts. Seems okay but I'll be back there in not too long. Back probe at ECM power harness reveals a blown fuse and a broken wire in the loom where it crosses between the frame rails. No change in the problem though... Do some more research through Cummins and come up with ECM needs to see 10.5 volts to power up. Okay I have in the neighborhood of 11v at the ECM harness as it has a dedicated power and ground. However, the switched power is supplied from the starter connections. Now I'm suspicious, to test my theory I set up my meter to test voltage at the power distribution block inside the cab (Supplies key switch/acc. power from the starter). During cold cranking voltage pulls down to 10.3-.4 range and slowly climes back. As soon as it hit 10.5v the truck would start almost immediately. With the engine warm the cranking voltage was 10.7 and the truck started fine. Performed voltage drop test on the battery cables and found 1.3v drop across the 2/0 positive cables. Replaced cables and truck starts consistently within 3 seconds. Previous crank times nearing 30 seconds.

Hours: 50

FQ2013

Continuing Cummins M11 fuel pump issues... I'm starting to feel pretty familiar with these by now! You may remember I was having problems with losing prime and well, it got a lot worse. Truck couldn't start on it's own anymore because it would pull the batteries down before it could self prime and purge the air. When I initially started working on this truck it would build 22 +/- psi cranking. When I pulled it in the shop it would barely make 10 which is no good at all. In my research I found a TSB from 15 years ago regarding above tank filter mounting. Apparently Cummins decided the best fix was a check valve in a fitting at the filter...

Along with a reman fuel pump I was sure the problem would be resolved. Nope, although the original pump had stripped the splines on the drive gear (Causing the low pressure) it was not the ultimate problem. With a pressure gauge hooked up while cranking it will read zero but spike up to 20 psi every 10 seconds or so until it starts. Hmmm, the check valve eliminated any drain back and air intrusion so what's going on now? FSS is 12v powered with ignition on but only "pings" while cranking (explaining the pressure reading). What the heck? According to Cummins the FSS is powered when the ECM senses the ignition is on and only turns it off with the key switch or engine over speed. On further research some ECM's are programmed to shut off fuel until it get's a reading from the engine position sensor. Performed Cummins ohm testing procedure and sensor tested out fine. I'm not sure I'm convinced that it isn't the problem though.

Week: 60

Wheel end control...

On the topic of ABS and stability control

Computer is getting feedback from wheel end sensors but they must be using individual leveling valves or a single modified valve that can control the suspension independently.

ABS valves

The brake modulator is used to control individual or in this case LH side of the tandem drive. Using the input from the wheel speed sensors the computer will command the modulator to cycle exhausting service brake air to the atmosphere and preventing the wheel from locking up. A three wire connector is used to control the inlet and exhaust solenoids in the valve. During normal operation the service air bypasses the exhaust port and is routed directly to the brake chambers.

And there were pictures...

In the process of repairing an intermittent short in the headlight system I found these. None of which were the problem.

The corroded off wire in the first picture was in the wiring loom directly behind the RH steer tire. No tape, shrink tube, etc... had been used. Someone then skived the insulation off of wire 22D coming out of the RH headlight relay and ran a light gauge jumper wire to front of the truck. A crossover wire was used to hook the headlights together but was left hanging across the front cross member. It is pictured below. I repaired the damage to the harness in the loom and completely re-did everything from the end of the frame rail forward. New pins in the metripac connectors at the headlights and the harness is now back to OEM original using numbered wire.

FQ2013

Learning the art of repairing what has been done before you... Driver complained of the headlights flickering on/off constantly. In the process of finding the short I found these. None of which were the problem.

... or not. Company phone won't connect to the server to upload the pictures. I'll put them up in another post as soon as it works.

Week: 50
Total: 418