4H Pull

Made a discovery today, in my '13 Taco!

When I engage 4H (and with my foot on the gas pedal), it pulls hard right. When I release the gas pedal, the pull goes away. Seems like that wheel hub is not engaging. I checked the ECU and transfer case wiring, to no avail (doesn't seem to me like the t-case would be the issue anyway, since the other side is driving). Taking it to the d'ship tomorrow. Anyone had this issue? Is there something to check on the front diff before I wait a day for them to perform a 30-second fix action?

I've researched this and found that the biggest culprit is wiring...and actuators. I've also checked the 4WD switch...it goes from 2H - 4H - 4L and back, with no issues.

 

Here's to hoping so...lol. To clarify, I release the gas pedal and coast while it's engaging...that's not clear in my original post. I had a 98 F150 with the shift-on-the-fly switch, and learned with her.

There's SOMETHING preventing the one side from driving...drat.

 

It's under warranty... don't sweat!

 

The OP is calling this a 4hi pull . Wondering if he is feeling some kind of torque steer . This would ofcourse mean WOT

 

This is very extreme for torque steer... Just my opinion.

 

Are you doing this on pavement? Driving in 4wd on pavement will definitely affect the steering, and I bet you are experiencing the truck pulling away from the crown in the road. I don't think it's really possible for just one wheel to receive power in the front of the truck with an open diff and an ADD that's not working.

 

I don't have the solution to your problem, but I have to share that I LOL'd when I realized that your 4H Pull wasn't a farming event at the county fair.

Mike

 

Tire pressures good all the way 'round?

 

Yeah...good all around. Initial test shows "a drivetrain malfunction," according to the d'ship. They seem to think the 3" Toytec lift is the culprit...mgr is in a test drive now.

 

No trips planned... but I would rather be in Baja!

Not sure if the axle spin question was totally answered, but thank you!

 

They flashed the ECU. What the...still there.

 

lol what in the world is resetting the ECU going to help? What type of road surface are you trying this on?

 

Dirt road...

 

More to come...

 

Are you sure Trac isn't engaging and braking one of your front wheels? My Trac system did a whole lot of what it wasn't supposed to do when I put a 3" lift on my 09 TRD Sport.

Try shutting of Trac/VSC by holding down the button for 5 seconds while at a stop, till it's indicator lamp lights up. Then see if it's still pulling, just to rule that out.

 

So, I just got home from the 2 dealerships:

Dealership #1 verdict: attributed to the geometry of the suspension, due to the lift kit. Flashed the ECU, "good to go." Obviously, it's not that simple. I just called them back to notify them that the flash did nothing for me. He'll call back after he talks with the tech...yay.

Dealership #2 verdict: they don't have a clue. It took them 1.5 hours to test drive it along with a new one...and tell me that it's not normal. They'll need the taco for "a day or so" to troubleshoot. I told the "advisor" I wanted to talk to the tech. The tech seemed knowledgeable (I know, I know) about the 4WD, transfer case, front diff, etc. He stated that the ADD would not be a cause for the pull. I asked him what the chances are that there's a bum component in the 4WD system, but he said small to none and thinks it's all about the lift.

I'm planning on dropping it off tomorrow AM, but I hate that they're blindly going into this. That said, I have no earthly clue where to begin...very frustrating. I've driven it in 4WD with A-Track and VSC on and off...no changes whatsoever.

Does anyone have anymore recs about what I can check for (vacuum hoses, relays, etc.) before dropping her off? I don't know where most of these components are located.

Thanks for all the feedback!

 

I have a 1.5 inch carrier bearing drop kit. Can't imagine that'd be the issue, as it is south of the transfer case...

 

If the ADD mechanism is jacked, wouldn't I get these symptoms?

Here's a good explanation: http://www.off-road.com/trucks-4x4/tech/the-automatic-disconnecting-differential-system-19259.html

 

If the ADD malfunctions, you wont get 4x4 at all. From my understanding of the ADD system and diffs, if the ADD was not locked, and power was being applied through the front driveshaft(transfer case is in 4hi), power would be wasted out of the diff to the non-locked, free spinning side of the diff that the ADD is on. Someone please correct me if I am wrong.

 

If that's the case, I've misunderstood. If I had the knowledge and facilities, I wouldn't be dealing with the stealership...lol