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2007 F350 HD Model 6.0 - ~170,000 with Edge CTS Programmer
History:
Failed Torque Converter (TC) at ~135,000 miles. Replaced Transmission with used one out of a 2004 with ~50,000 miles on it. Put in brand new OEM TC. No transmission issues until now ~35,000 miles.
Issues I have observed:
Fuse box in engine compartment missing cover. Admittedly didn't really consider the implications of this (stupid as I am an Electrical Engineer)
Battery hold down came loose while off-road and battery "jumped" and broke plastic covers off PCM connectors, no damage to engine harness wires but Trans harness wires had some insulation nicked off but none broken. Covered nicked wires with liquid electrical tape.
Additionally I admittedly routed the Trans harness incorrectly when reinstalling it and zip-tied it to the frame above the fwd drive shaft instead of under... the harness sagged and caused a short in the transfer case wiring which caused an erroneous shift to 4wd (luckily not at fast speed and I immediately shifted to neutral and stopped the truck). I repaired the broken wires and the truck has operated fine until now ~5,000 miles.
What Happened:
Driving home from work and noticed heater not working... stopped and found coolant evidence on coolant recovery bottle and surrounding area... also started noticing hard shifts... drove directly to the auto parts store (~15 miles) got new cap because cap failed and refilled with coolant. Heater now works! Started driving home and got the tow/haul light blinking and truck responded as if in neutral in all gears... read the following codes from the Edge: P0700, P0766, P2703. I was able to use the edge to reprogram the PCM/TCM and the truck would drive and shift fine for about a mile or so and then repeat but depending on the gear I was in at the time the codes would change to the corresponding solenoids (I think). I made it home this way and parked the truck in the garage where I started looking for problems.
What I have found/done:
Pulled negative battery cables and checked resistance to ground from the positive terminals... it was low ~1.3Kohms. I began cleaning all connectors around PCM and realized the fuse box without the cover... (dumb me) so I pulled this apart and cleaned everything with contact cleaner and blew dry... reassembled everything and got resistance into the ~.7 Mohm range (making assumption that this is capacitance to ground). Tried to test drive the truck worked fine shifted fine went about 5 miles and then turned around and drove home... just about the time I got onto my road... tow/ haul with only the OSS code P0721 but truck acts as if in neutral again... reprogrammed with Edge and got it back to the garage. Swapped the OSS sensor with a good spare I had from the transmission replacement I did... same issue again. I decided with the issues I had with the Trans Harness to get a new one (brand new)... replaced it... I did a Return to Stock with the Edge and tried to drive it... P0700, P0751. Tried to program it back to Economy and the Edge said it couldn't because a file was missing or corrupt... did firmware update on Edge... reprogrammed PCM successfully... back to driving good for about 2-3 miles and tow/haul, P0721 and acting as if in neutral.
Took truck to Ford thinking this might be a programming issue... had them do an as-built flash... they call me and say it is still giving the P0721 and he thinks it is the PCM... I ask him if he is sure (expensive part) he says let him run some more tests... he comes back and says he drove the truck with the computer hooked up and got good pressure but in reverse it was a bit low but thinks it is a direct clutch issue because the pressure spiked to 300 when the trans tried to shift to 5/6 gears. He wants to drop the transmission...
I really doubt it is a programming issue. 99% of the time when I've seen problems similar to this it is due to a problem with the wiring harness. I HIGHLY suspect where you made the "repair" with liquid electrical tape. How were the wires inside the insulation? Any broken? Any higher than normal resistance circuits there?
Is it a possibility when the battery jumped it jarred something in the PCM? I realize those are fairly stout connectors, however those plastic covers don't take a ton of abuse.
Any other splices anywhere you may have done and overlooked? Did you repair the PCM plug covers?
As for the PCM I don't know... but I would think if there was something wrong with it that should have been caught when the tech did the as - built flash?
As for the PCM Connectors... the 1st 2 (from left to right if you are looking at the connectors from the front ) just had their plastic covers cracked... no damage to the wires. The last connector (trans harness connector) has been replaced with new.... and lastly other than the splice on the OLD trans harness I haven't touched any of the wiring.
I really doubt it is a programming issue. 99% of the time when I've seen problems similar to this it is due to a problem with the wiring harness. I HIGHLY suspect where you made the "repair" with liquid electrical tape. How were the wires inside the insulation? Any broken? Any higher than normal resistance circuits there?
Sorry if I didn't make it clear... I replaced the entire trans harness with a brand new one.
I am contemplating having the Ford dealer do a "Hot Flush" on the trans as I was due for a fluid change anyway... to see if maybe I have something that is clogging a port? Does this make any sense or am I just shooting in the dark? They want about $200 to do this...
I am contemplating having the Ford dealer do a "Hot Flush" on the trans as I was due for a fluid change anyway... to see if maybe I have something that is clogging a port? Does this make any sense or am I just shooting in the dark? They want about $200 to do this...
Not that a hot flush is ever a bad idea in terms of maintenance but I doubt it will resolve your issue.
Not that a hot flush is ever a bad idea in terms of maintenance but I doubt it will resolve your issue.
I appreciate the input Shane but why do you think that?
So far my thinking is that I have eliminated the wiring (brand new harness), thinking I have eliminated the PCM (I would think it would have had an error when trying to do the As-Built flash), which only leaves something internal?
But since I could reset the codes and get it to shift through all gears for a period of time I am hoping no major damage... thinking maybe the flush would push anything out restricting flow?
Just thinking out loud... definitely open to suggestions.
I'm not following your logic. You think that there is something internal that is causing the problem. But when you reset codes it works for a period of time. If there was a blockage causing this, how would the blockage know to move out of the way when you reset the codes?
Reflashing won't always find a problem with a PCM. Though I really doubt that's your problem.
I'm getting confused with all the current and past symptoms. What codes are setting now with the new harness?
I'm not following your logic. You think that there is something internal that is causing the problem. But when you reset codes it works for a period of time. If there was a blockage causing this, how would the blockage know to move out of the way when you reset the codes?
Reflashing won't always find a problem with a PCM. Though I really doubt that's your problem.
I'm getting confused with all the current and past symptoms. What codes are setting now with the new harness?
Okay... sorry for my ignorance and the confusion...
After replacing the harness and doing the as - built flash this is what the tech saw:
Drove out of shop and parked truck... went to get something came back and had the P0720 and safe mode...
Shut off truck and waited for a few minutes... started truck with computer hooked up and saw pcm communicating with oss.
Drove truck and got codes P0720, p2703 and p0766
Parameters that computer saw:
Pressures
Reverse = slow increase to 80 then jumped to 300
1 - 3 = 72 (good)
5,6 = jumped to 300
No, I don't. That won't cause the P0720, which seems to be the root problem here. Usually that's an issue with wiring. But I've also seen a bad diode in the alternator cause a P0720. The bad dipode adds an AC component to the system voltage. The PCM sees this variation as a reading from the OSS. It sets a code because the OSS readings are unrealistic.
Can you measure the truck's voltage to see if there is an AC component? Alternatively, disconnect the alternator and see if that corrects the problem.
No, I don't. That won't cause the P0720, which seems to be the root problem here. Usually that's an issue with wiring. But I've also seen a bad diode in the alternator cause a P0720. The bad dipode adds an AC component to the system voltage. The PCM sees this variation as a reading from the OSS. It sets a code because the OSS readings are unrealistic.
Can you measure the truck's voltage to see if there is an AC component? Alternatively, disconnect the alternator and see if that corrects the problem.
Wow... I wish I had known that a while back... I didn't even think to mention that when I was troubleshooting the resistance to ground and I disconnected the batteries that I found the one on the passenger side severely discharged compared to the driver side battery... but the twist is I disconnected the alternator and took it and the batteries to O'Reilly's Auto and had them tested and other than the one battery being low on charge they said everything tested good. I will have to try that tomorrow.
12-21-2015, 05:26 PM
