Engines 2014

Having a steel pin put in my hand has slowed me a down a bit... I was helping Joe with the CAT but have had to leave early for doctors appointments unfortunately. I did the research assignment on the Maxxforce.

The cold start system used on Maxxforce engines is inactive above 50 degrees. This isn't in the manual but from personal experience with these engine if the ECM commands cold start assist the engine will not start until it has completed its cycle (cranks but doesn't fire). I wonder if there is a start inhibit until it cycles off? They use a grid heater with a low pressure fuel injector. This is installed in the intake and when active fuel mist is drawn across the grid heater element. It cycles on and off for a time after the engine starts.

I've tested thermistors in an A/C system using the palm of my hand and watching the readout with International BodyBuilder software

A thermistor sensor changes electrical resistance with
changes in temperature. As temperature changes
at the thermistor, voltage at the ECM will change
accordingly. Thermistors work with the control module
to produce a voltage signal directly proportional to
temperature values.
A thermistor sensor has two electrical connectors,
signal return and ground. The output of a thermistor
sensor is a non-linear analog signal.

I've tested magnetic pickups when troubleshooting an engine speed sensor on a Detroit 60 when the tach was inop. Found a clear pulse but the 0.2v reference dropped off when the gauge was plugged in. Found some damaged wiring.

A magnetic pickup sensor contains a permanent
magnet core that is surrounded by a coil of wire.
The sensor generates a voltage signal through the
collapse of a magnetic field created by a moving metal
trigger. The movement of the trigger then creates
Alternate Current (AC) voltage in the sensor coil.

I've tested a potentiometer when working on a Freightliner with surging problems. Ended up replacing the throttle pedal assembly.

A potentiometer is a variable voltage divider that
senses the position of a mechanical component.
A reference voltage is applied to one end of the
potentiometer. Mechanical rotary or linear motion
moves the wiper along the resistance material,
changing voltage at each point along the resistive
material. Voltage is proportional to the amount of
mechanical movement.
The engine has two potentiometers, both contained in
the Accelerator Pedal Position (APP) Sensor.

Week: 40
Total: 290

SPQ2014

Somehow I'm the APU guy now... ThermoKing has some interesting service procedures. Refrigerant capacity of 1.2-2 lbs (Nice of them to give a definitive answer). Once you've added enough refrigerant to run the system you work it to it's max and add an ounce at a time while watching the sight glass. When it's clear at 150 psi you're good.

Had some trouble with a Ford Hydro-Max brake system. Pedal pulsed intermittently with the park brake released. I found a Bosch service guide (Bendix valve... Figure that one out) for it after searching through way too many websites.  The park brake valve was leaking internally and relaying it into the foot pedal.

Did some work with CAT's Electronic Technician. No cruise control and I found the brake switch for the computer had a 10v drop across it when closed.

Week: 50
Total: 250

SPQ2014

Becoming familiar with Paccar's new MX engine doing some recall work. Learning the "times" of warranty work... Paccar says it takes 0.9 hours to change the crankcase vent module and it took 5 hours Friday night. I did my second one on Saturday in 2 hours. I think I've figured out how to it a little faster but I'll still be an hour and half. Everything is so well fit together that one has to get creative with swivels and wobbly's to get at anything.

Worked on a newer Kenworth that the towing company brought in after they couldn't fix the brake lights. When I got into the fuse panel and saw jumper wires going across the front I had a bad feeling I knew what was wrong. Further inspection revealed a technician induced failure. Someone had obviously done some probing with a test light and spread the fuse terminals. Unfortunately you can't repair the fuse block. I pulled it thinking I could get in through the back but it's permanently assembled in 3 layers (Rear connections, circuit board, and the fuse/relay side). $1,000 fuse block ruined because someone didn't take the time to do it right.

My assigned "sensor" is actually a lift pump off a Cummins ISX. The seal between the pump housing and flange usually fails. It is a very small vane pump. I was able to find a diagram for it.

Parts have started coming in for my wiring project.

Week: 50
Total: 200 hours

SPQ2014

This is what helped me understand how a diode works http://electronics.stackexchange.com/questions/54977/how-does-a-diode-work

I've been doing a lot of electrical and suspension work lately. 2011 F-350 with inop work lights... An hour of following wire harnesses later I found the fuse block under the rear seat. I kind of like the setup and may do something similar with the wiring in my own truck. Keep all the relays and fuses out of the weather that way.

Also worked on a Kenworth with a tach that wasn't working. The fleet had replaced the tach and the sensor but it still wasn't working. Unplugged the gauge and had 12v power and ground with a 0.2v AC signal. Plugged the gauge back in and back probed it. The signal voltage dropped off completely as soon as you plugged the gauge in so I knew I had a wiring problem. I ended up finding the wires worn almost all the way through on the back of the engine block behind the exhaust. That was interesting trying to reach in with all my wiring tools behind the exhaust.

Did an alignment for the first time this week. Pretty easy actually. Also did all the boards this week with Travis again.

Week: 50

SPQ2014

Re-learned how to find a short this week... Had to stare blankly at my meter until it came back to me. Haven't needed to find many shorts recently. Working with Travis helped me out because he remembered some things I didn't. Got all of the lamp boards done and did the shorted boards as well as the fan motor boards. Did the 101 electrical self test too.

Well, a 1/4 steel plate can look nice but it takes some time with a 9" grinder.

Used Cummins EDS to diagnose a regen problem on a LTI truck on Saturday. They had changed the EGR valve but were still having problems and found the EGR differential pressure sensor had failed.

Week: 50 hours

Winter 2014

Been doing some clean work lately... Fenders and lights on a 2015 Kenworth

Air solenoid valve for the interlock on a Volvo shorted out and kept blowing the fuse

ProStar was reading out on the speedometer while parked. Found the ECM harness rubbed on the ECM mounting bracket

I got a new tool box so now I have room to lay all of my tools out

Refer Training

I'm currently sitting in PHX Phoenix Sky Harbor waiting for my flight out at 6:40... They flew me out here for an Idealease Transport Refrigeration class. It's based on ThermoKing and Carrier's two week training programs and then condensed down into a 4 day class for Idealease. I took the test for my Universal/608 certification allowing me to legally work on any refrigeration system not covered by EPA 609 (Automotive A/C systems). I've never learned that much in 4 days before... Time to go home.

We currently do no work on trailer refer unit's at all and are not even set up to recover R-404A and I'll be the only one that can even legally touch a refer unit. It looks like we're going to get into refer service (or at least our leasing side will be) and they must be confident that they'll have work because they dropped over $3,000 for me to go to this class.

Learned quite a bit and I can honestly say that I think I could solve most anything wrong with a ThermoKing unit now. The electrical systems are simple and the wiring schematic is well laid out. LED indicators in the circuit board, self diagnostic abilities are amazing... I can shut the unit down and command individual solenoids and functions to cycle for up to 15 minutes. They put highway trucks to shame for diagnostic functions. Going into this I didn't know hardly anything about even a basic A/C system and now I actually understand how and why they work.

I was surprised that only 4 people were in the class (This is for the entire western sea board) but at the same time I think I learned a lot more that way.

Last two weeks: 80 hours