2007 6.0L random starting issues

Brad Clayton · December 30, 2013

I have F-550 manual trans 4x2 with a service body that is freighted. It was towed in last Friday before last for a crank no start. The driver said he pulled a code for a PCM "bad" and cleared said code. I verify a nice strong crank but no start.

The first thing I notice is the cluster warning lights are very dim. There are no codes except for an IC communication code. The next thing I notice is there is no injector buzz at key cycle. I pull up pid data and then lose it the instant I crank the engine over (as if the DLC were unplugged).

I turn the key on and off a few times and notice that every once in a while the cluster lights will be nice and bright like normal and the injectors will buzz, however once the key is turned to start, it's all back to the dark ages. So I jumped the starter under the hood and it runs just fine.

I dig into the ignition switch and find no power out of the red/green wire when this is going on and the wire has been "T" tapped multiple times in the past. I replaced the ignition switch and the wire terminal. Truck starts normally and no codes, pid data is spot on and cluster lights work as designed. I release the truck and it runs fine for the next 6 days.

Get a call today that the truck wont start. Go down to take a look at it and the batterys are hammered. Bring two batterys and the IDS and get it started without too much issue. Now I am back at the shop and have no codes and it starts every time, however..........I am seeing something odd on the pid data that I have never encountered. Once you engage the starter the pid data will freeze for a second or two and then the truck starts and pid data resumes operation.

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Notice where the cursor is at around 2 seconds and 0 RPM.

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Now if I hover my mouse over the small increment arrow and hit it once, the time cursor jumps immediately to around 4 seconds and 616.75 RPM. All the data in between is not readable.

It's as if the truck gets confused for a second or two and then acts normally. You can see the graphs are still registering however the data can not be looked at in numbers on the left. When the truck is cranking the ICP hangs at 133 PSI, truck starts and then it resumes with the data at the 4 second mark.

Anybody had issues with shit hanging up like this?

Bruce Amacker · December 30, 2013

I haven't seen this one, but when you have a shorted injector the PID data drops out while cranking. Just for fun, run the buzz test and verify all are present. Crank it with the FICM relay pulled to see if things still act weird, if they don't it might be a shorted injector. The problem is the 48v spiking back through the ground side and pissing off the PCM. I've seen it twice (remotely).

Good Luck!

:grin:

Matt Saunoras · December 31, 2013

Not personally but my buddy who's a diesel tech at another dealer had a no-start possibly RFI problem caused by the starter. The only thing he noted was the starter did sound odd while cranking. The truck did get a main engine harness before the starter was deemed the cause.

Brad Clayton · December 31, 2013

Interesting. I did a buzz test with all reporting normally, unplugged the FICM relay with no change, and unbolted the glow plug/alt wire from the battery and retried with no change. I will look into this starter thing tomorrow.

Brad Clayton · December 31, 2013

Updates: monitored pid data while jumping the starter solenoid under the hood and data streamed correctly. Used key again and data would lock up. I ruled out the starter as the culprit.

So looking at the EVTM and the ignition switch circuit, I found fuse 45 comes off the run start leg to the IC. I removed fuse 45 and data streams during start, put fuse back in and the data locks up and the cluster warning lamps are dim again (original concern). So I am going to delve further into this U1900 code for the IC and see what I can see.

mchan68 · December 31, 2013

Updates: monitored pid data while jumping the starter solenoid under the hood and data streamed correctly. Used key again and data would lock up. I ruled out the starter as the culprit.

So looking at the EVTM and the ignition switch circuit, I found fuse 45 comes off the run start leg to the IC. I removed fuse 45 and data streams during start, put fuse back in and the data locks up and the cluster warning lamps are dim again (original concern). So I am going to delve further into this U1900 code for the IC and see what I can see.

Please do report your findings on this, since I have had many trucks coming in with this particular DTC set as well (including my own truck) that I've never had to dive any further into, due to no driveability or starting issues present.

Alex Bruene · December 31, 2013

Not personally but my buddy who's a diesel tech at another dealer had a no-start possibly RFI problem caused by the starter. The only thing he noted was the starter did sound odd while cranking. The truck did get a main engine harness before the starter was deemed the cause.

Been there. What a See You Next Tuesday that was to figure out!

Brad Clayton · December 31, 2013

Alright so the U1900 was being reported by the IC from the ABS module not being configured correctly. I can't get this thing to bring up an as built data screen to save my life. So I just unplugged the ABS module and got it right out of the loop. I have unplugged all sorts of stuff, ICP, EBP, FICM, GPCM, took the IC off-line and still no avail.

I have got the vehicle to act up for more than 2 seconds though. It stayed in break down mode for about 30 seconds one time and I tugged and wiggled harnesses everywhere I could get at. I unplugged the fan and things worked great for a moment.

Still battling it at the moment.

Brad Clayton · January 5, 2014

Not calling this one fixed, but it's back in the customers hands at the moment. I hooked up a voltmeter to the vref on the egr valve and it would get pulled down to 0volts during the event. I started at the harness inside and moved through the firewall and back to the PCM. The only thing I noticed was the wiring harness trapped under the battery tray, but they all are like that. I removed the tray anyway and split the harness open and the br/wh wire for the 5 volt ref was actually rubbed. I replaced that section of wire and reassembled and have not recreated the concern yet.

Brad Clayton · May 1, 2014

This one came back today. Doing the same thing. I showed the driver how to get it running as he needed the truck and he is going to bring it back Monday. Hopefully I can get it to act up long enough to pin it down this time. Really not sure which way to go with this thing.

mchan68 · May 1, 2014

Being a manual transmission, MAKE SURE IT'S IN NEUTRAL when he jumps the jumper under the hood. :haha2: :haha2: :haha2: :haha2: :haha2:

8WA Sman · May 9, 2014

Updates: monitored pid data while jumping the starter solenoid under the hood and data streamed correctly. Used key again and data would lock up. I ruled out the starter as the culprit.

So looking at the EVTM and the ignition switch circuit, I found fuse 45 comes off the run start leg to the IC. I removed fuse 45 and data streams during start, put fuse back in and the data locks up and the cluster warning lamps are dim again (original concern). So I am going to delve further into this U1900 code for the IC and see what I can see.

Have you tried by-passing the clutch pedal position switch. According to the EVTM I am looking @ the clutch switch is tied into a PCM VREF and a PCM Low REF.

Brad Clayton · May 9, 2014

Replaced engine harness on Monday and so far so good 5 days later.

Brad Clayton · April 22, 2015

Well this one has been acting up still. I showed the customer how to get it running when it acts up and they have been dealing with it for the time being. It finally laid down and they towed it in, however it started for me. I went to lunch with the guys from the company that owns the truck, today and they told me the truck had a remote shutdown/start system in the rear.

This setup is used for the boom and I am willing to bet it is what is causing my problems. Hopefuilly I will have some answers by the weekend.