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2004 Ford F150 5.4L with P0734 and P1000: Overdrive Failure After OBD2 Scanner Connection

Model: 2004 f150 5.4l Fault Code: P0734 Posted: 2017-01-17 06:40

I recently visited a shop for an alignment, which required connecting to my vehicle's OBD2 port using the Edge programmer. The technician removed the Edge unit temporarily during the process and reattached it afterward. Since then, I've experienced intermittent overdrive failure. The issue occurs when I reach approximately 25 mph—after that point, overdrive disengages suddenly, causing the truck to behave as if it has no transmission. I must manually turn off overdrive for normal operation. I’ve confirmed with Edge that my programmer is up-to-date and set to stock configuration. The P1000 code persists even after clearing it, and while a brief transmission fault appeared on my gauge display once, it hasn’t reappeared. Based on research, the P0734 and P1000 codes are not typically directly linked, yet both surfaced at the same time. The overdrive function works normally until the transition point—this suggests an electronic or sensor-related issue rather than a mechanical transmission failure. I’ve performed additional testing: when driving on a busy road and reaching 40 mph, the truck immediately loses overdrive as soon as it engages, then functions properly once I disable overdrive. My vehicle has undergone standard maintenance including spark plugs, coil packs, throttle body spacer, cold air intake, and exhaust modifications. No other components have been added or modified beyond these. I’m seeking advice on how to diagnose and resolve this issue—especially since the problem only started after the OBD2 connection event.

Related fault codes

P0734P1000

Comments (7)

Anonymous 2017-01-17 08:45

Are there any other diagnostic codes present? Try using a different OBD2 scanner to verify the fault codes. Consider disconnecting the Edge programmer temporarily—especially since it's not a factory component. Is your vehicle stock (aside from the Edge)? Are there known issues that could prevent transmission monitor runs?

Anonymous 2017-01-18 07:18

I have an alternative code reader I'm testing now. The only modification on my truck is the Edge programmer, which has been set to stock settings since the issue began. I spoke with Edge support—they ran a full scan and found no issues. During further testing yesterday, I discovered that speed isn't the trigger—it's when overdrive first engages. On a highway run at 40 mph, as soon as overdrive activates, the truck suddenly behaves as if it lost transmission control. Turning off overdrive resolves the issue immediately. The only modifications to my truck are standard maintenance: plugs, coil packs, throttle body spacer, cold air intake, and exhaust.

Anonymous 2017-01-18 08:21

Try using a different OBD2 scanner—quick, free, and easy to use. I suspect there may be underlying codes if the behavior is as described. Try shifting into second gear—does engine braking occur?

Anonymous 2017-02-28 08:45

Apologies for the delay—I had a driveshaft carrier bearing failure that required repair. I waited until after taxes to get it fixed, and now it’s been replaced with new u-joints, slip yokes, and a replaceable carrier bearing (about half the cost of a full driveshaft from Ford). Before the failure, I noted some diagnostic codes—now I can’t find my notes. The current code I have is P0356. Engine braking works properly when in second gear.

Anonymous 2017-03-01 15:06

P0356 relates to misfires and coil issues, but my truck runs perfectly under all conditions. I’ve experienced coil failures before and can recognize the symptoms—this is not a misfire-related issue.

Anonymous 2017-03-01 16:20

I found my original note—the previous code I had was P0734, which may help clarify the issue.

Anonymous 2017-03-01 17:01

https://www.obd-codes.com/p0734