4r100 Ford transmission 2000 Ford Lightning

KEN BARNETT

MEMBER
2000 FORD F-150
5.4L
V8
2WD
AUTOMATIC
50,000 MILES

2000 Ford Lightning 4r100 trans. Intermittent lock up and stalling when put into forward gear. Sometimes when at stop light it will lurch forward and stall. No problem going into reverse. Transmission will only downshift into 2nd gear and not into low when coming to a stop. Will not shift into overdrive. No problem shifting 2- 3 and shifts smoothly. No slippage anytime.
Trans. Fluid was changed along with filter. Fluid was red when removed, no odd smell or discoloration. Shows code po743
All wires and connectors clean no breaks in circuit wires. Checked wires for continuity. Engine runs smooth. All vacuum lines checked and/or replaced. Voltages have all be checked tps, ICV solenoid was replaced along with IAT

1 Reply

HMAC300

MECHANIC
48,601 POSTS

This may be an internal problem if all wires have been checked to trans/tcm for shorts/grounds etc. I'm including a tip about third brake light it uses same circuit as tcc and if bulb is burnt out then it will set the code you have. But from your description i'd have a trans guy look at it for a better diagnosis. Being a lightning it may have been abused prior to you getting it so reason for screwy down shifts/up shifts. It may be an internal problem. There is also the 16 yr old factor. If you have a teenager hard telling how it has been driven. It kind of sounds like it 's trying to go to limp mode due to internal damage. Like a bad seal/converter

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