P0750 - will not go away, tried everything.

Dirtman · Nov 23, 2018

I still have ALL gears functioning and shifting properly which is why this is so frustrating.

I finally got my atsg for the 5r55e today. Only relevant info I found so far was

"code P0750 - SS1 circuit failed to provide voltage drop across solenoid - Circuit open or shorted or pcm driver failure during onboard diagnostics."

with no problems shifting or loss of gears and basic circuit testing proving good I'm left with a pcm driver error?

I bought a new DTRS today, got too cold to install it yet. It was messed up anyway so if this does nothing I think I may be stuck looking to have the dealer flash/upgrade my pcm?

Dirtman · Nov 24, 2018

Installed the new range sensor, the column shifter works 100% better lol. I doubt it fixes the p0750 but itll take at least 150 miles to tell.

Dirtman · Nov 28, 2018

Update. I finally figured out how to read the PIDs for the range sensors voltages. Everything is in spec. 1.6 volts.

Then I decided to drive around with my scanner set to display the gear commanded, rpm, vehicle speed, torque conveter clutch status and solenoid status and found something odd.

My scanner never sees a command for second gear. Even when I manually put it in second gear it reads 3rd. According to the scanner it shifts from first to third. And then when in fifth (its actually in 4th) it ignores the final switch into overdrive?

Is this just my scanner being stupid? You can clearly see it shifts from 1st to third and then its doing 2600rpm at 55 mph in 5th gear. On the highway when its really in 5th gear its about 2400 at 65mph.

I made a crappy video (didnt get fast enough to get into real fifth but you can see what I mean about never showing a command for 2nd gear) im wondering if this is because of the 5r55e's "fake" second gear maybe the scanner is confused? It does in fact shift through 5 gears... nothing missing.

sheltonfilms · Nov 28, 2018

I think that’s just because it’s a 5r transmission. 2nd manual is 3rd gear.

2nd In od is really 1st first gear with overdrive applied.

5r is essentially a 4R with an extra gear (2nd, 1st overdriven). Not a physical new gear but a shift strategy.

I would look at ratio commanded and ratio actual if that is what I remember correctly is the pid names.

Sent from my iPhone using Tapatalk

Dirtman · Nov 28, 2018

sheltonfilms said:
I think that’s just because it’s a 5r transmission. 2nd manual is 3rd gear.

2nd In od is really 1st first gear with overdrive applied.

5r is essentially a 4R with an extra gear (2nd, 1st overdriven). Not a physical new gear but a shift strategy.

I would look at ratio commanded and ratio actual if that is what I remember correctly is the pid names.

Sent from my iPhone using Tapatalk

This is kinda what i was thinking.

So far the p0750 is still not back but im only at 75 miles since the last reset & range sensor replacement.

Ill take another ride with the gear ratio PIDs up.

Dirtman · Nov 30, 2018

Took a drive with the following PIDS up. Commanded gear ratio, actual gear ratio, input sensor speed, output sensor speed, engine rpm, gear commanded, touque converter clutch percentage, and tourque converter slip.

Gear ratios did not match what they should be

5r44e specs are
First - 2.47
Second - 1.86
Third - 1.47
Fourth - 1
Fifth - .75

Again my scanner showed it skipping second by going straight from 2.47 to 1.47 ratio.... Never hit 1.86

And while it read fifth gear and ratio reading .75 the input and output speeds were reading almost identical indicating a 1:1 ratio (fourth gear). And then as I increased speed it would shift into real 5th gear and output speed would increase about 700-800 rpm above input speed which would be proper overdrive but gear commanded and ratio didnt change.

So in a nutshell my scanner goes first, third, fourth, fifth, and then ignores the real final shift.

At this point Im just assuming my scanner sucks and cant properly decipher the data from the goofy fake gears and electronics in the 5r44e.

P0750 still off after 100 miles though....

Transman304 · Dec 1, 2018

It won’t have second on the scanner same as fifth gear. These are strictly based on what the PCM determines it needs under certain conditions. Not designed to be there for every shift cycle. You have to monitor solenoid activity to see what it is commanding. Now put the scanner away and put some miles on the truck to see if you have the P0750 fixed! Lol! Good luck :icon_thumby:

sheltonfilms · Dec 1, 2018

The RPMs syncing and then differentiating sounds like the Torque converter locking and unlocking.

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Dirtman · Dec 1, 2018

Transman304 said:
Now put the scanner away and put some miles on the truck to see if you have the P0750 fixed! Lol! Good luck

Good advice!

After I get over 300 or so miles without the code coming back I will start celebrating but until then I'm just gonna leave it alone and stop letting it get to me. My mechanic mind just has a habit of not letting things go without solid answers. And this has just been one of those problems where maybe its fixed but I'll never really know what I did to fix it lol.

Dirtman · Dec 25, 2018

Well I just passed 450 miles and the light has not come back... obviously the range sensor fixed the problem.

Oddly enough I finally got my factory service manuals which describe the shift patterns. Apparently 2nd gear simply isn't used 99% of the time. The first to third shift i was notcing on my scanner is completely normal as it will only command 2nd during wide open throttle or random downshift/upshift situations. Pretty interesting. So if you have a 4r55e and not a 5r55e you aren't missing anything!

It also specifically lists p0750 as an "electrical fault only", its interesting how a obd2 code definitions can vary depending on the specific vehicles parameters for the code. Anyway there are 10 pages on test procedures which state the range sensor must be tested and within spec before proceeding lol. Never would have guessed a glorified neutral safety switch could throw solenoid codes.... of course the testing procedures that follow cannot be done by mortal beings since they are written for ford techs with ford diagnostic gear that can physically command the solenoids on/off. I know of no scanner less than 2 grand that can do that. My humble 300 dollar scanner can read the solenoid PIDs but has no access to control them.

Still the service manuals have proven well worth the 150 bucks I spent on them. They make chilton/haynes manuals look like dr. Suess books.

P0750 - will not go away, tried everything.

Dirtman

Former Middleweight Moss Fighting Champion

Dirtman

Former Middleweight Moss Fighting Champion

Dirtman

Former Middleweight Moss Fighting Champion

sheltonfilms

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Dirtman

Former Middleweight Moss Fighting Champion

Dirtman

Former Middleweight Moss Fighting Champion

Transman304

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sheltonfilms

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Dirtman

Former Middleweight Moss Fighting Champion

Dirtman

Former Middleweight Moss Fighting Champion

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