Possible limp mode?
Thread Starter
|
Mountain Pass
Joined: Sep 2016
Posts: 229
Likes: 0
Possible limp mode?
I’ve got a 1999 Ford F-250 super duty 5.4 2v w/ 4r100 trans and I think my trucks in limp mode
I’m getting these codesP0743 torque converter clutch solenoid circuit electrical
P0755 shift solenoid B
P1747 pressure control solenoid A short circuit
the motor runs and idles fine but but when I give it gas and does not move at all. I can unplug everything on passenger side with no effect on the motor but if I unplug anything on the driver side and it dies out or idles super low like it’s not firing on that side at all (35’s w/ 8 inch lift) fuel pump and filter are new, upgraded injectors were already ordered prior to this problem and should be here Monday.
I’m getting these codesP0743 torque converter clutch solenoid circuit electrical
P0755 shift solenoid B
P1747 pressure control solenoid A short circuit
the motor runs and idles fine but but when I give it gas and does not move at all. I can unplug everything on passenger side with no effect on the motor but if I unplug anything on the driver side and it dies out or idles super low like it’s not firing on that side at all (35’s w/ 8 inch lift) fuel pump and filter are new, upgraded injectors were already ordered prior to this problem and should be here Monday.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
Likes: 2,625
From: SE Florida
You have three electrical fault codes for the transmission. The P1747 is causing your problem. If the pressure control solenoid is shorted it will be stuck at low pressure. The failure mode software limits engine torque to save the transmission. You MUST fix the wiring problem that is causing this code to fix this.
Thread Starter
|
Mountain Pass
Joined: Sep 2016
Posts: 229
Likes: 0
Well I did a compression test today on the side that doesn’t get affected when everything unplugged and cylinder 1 had 165 psi, cylinder two have just under 120 psi and cylinder 3 was at 100 psi at this point I know I have a problem with the motor itself and I believe it jumped a tooth or more possibly
Senior User
Joined: Dec 2003
Posts: 123
Likes: 0
From: Kearney NE
You have three electrical fault codes for the transmission. The P1747 is causing your problem. If the pressure control solenoid is shorted it will be stuck at low pressure. The failure mode software limits engine torque to save the transmission. You MUST fix the wiring problem that is causing this code to fix this.
this should help with drivability issues, then you will see how the engine is affected by the low compression numbers.
Thread Starter
|
Mountain Pass
Joined: Sep 2016
Posts: 229
Likes: 0
So I just finished redoing the timing and I know it is 100% correct it sucks I didn’t see the last reply until now. So correct me if if wrong but your saying that since it’s in limp mode it’s limiting the performance of the motor? And I need to replace the shift pack in the trans? I’m now getting codes for shift solenoid a-b and the torque converter clutch solenoid. Motor is freshly rebuilt and bored 20 over everything besides the block is new so I’m thinking of putting in a shift kit in it along with a shift correction kit while I’m in there https://www.thoroughbreddiesel.com/k...saAinNEALw_wcB
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
Likes: 2,625
From: SE Florida
I don't think I said to replace ANYTHING. You first need to diagnose what's wrong. I said it is most likely a wiring issue. IF you replace the solenoids and the problem is the wiring you'll still have the same problem.
Thread Starter
|
Mountain Pass
Joined: Sep 2016
Posts: 229
Likes: 0
10-4 I’ve looked at the connectors and the wiring on the trans but didn’t follow it all the up so I’ll do that when I get a chance
Trending Topics
Thread Starter
|
Mountain Pass
Joined: Sep 2016
Posts: 229
Likes: 0
So here’s my follow up I pulled the trans wiring harness out of the vehicle completely to thoroughly inspect it found no freys anywhere there was a section that the wire loom was torn and that looked fine too so I’m gonna clean up the connectors and reinstall. What’s the next thing I should check?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
Likes: 2,625
From: SE Florida
You should check the harness. Looking for frays and problems is nice, but it sure doesn't tell you that the harness is good. You need to check the harness electrically or you are just wasting your time.
Thread Starter
|
Mountain Pass
Joined: Sep 2016
Posts: 229
Likes: 0
UPDATE: finally got to taking the pan off and checking the solenoids I pulled it out and checked the ohms and put 12 volts to them all are right around 21 ohms and have a good healthy click except the bigger one on the plug side that was was reading about 4 ohms and was a lot less of a click
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
Likes: 2,625
From: SE Florida
Sure, rebuild the trans. Once that's done and you still have the same problem, and you will, you can troubleshoot the wiring harness to find the original problem.
THE PROBLEM IS THE SHORT CIRCUIT.
THE PROBLEM IS THE SHORT CIRCUIT.
Thread Starter
|
Mountain Pass
Joined: Sep 2016
Posts: 229
Likes: 0
i took the harness out and unwrapped it completely and still haven’t found anything what else could I do to check for shorts? There is a spot on the harness that’s black from an exhaust leak but it isn’t melted it’s just built up soot. Also the only gears I have is park and reverse I can feel drive engage because it moves a little but that’s it