TOD Issues - Random 4lo when on Auto

[WyldWeasel]

Hi Everybody. Been a while since I've posted. Life has been demanding.

Anyway, having trouble with my '99 VX of late: TOD randomly goes into 4lo when on Auto. Usually right after starting up. It happens most often when reversing out of a parking spot with a hard turn, accompanied by a hard chirping of the passenger front tire and a grindy noise from the front differential. Stopping the car and going into neutral and playing around with the 4lo 4hi lever doesn't help, but turning the car off for a few minutes and turning it back on sometimes fixes the issue. Sometimes it won't come out of 4lo at all so I park it and leave it overnite and it heals itself in the morning. It also happened once when car was underway, when slowing and turning left into parking lot, it suddenly went into 4lo and the CHECK TOD light went on.

Where should I start looking to diagnose this?

[tom4bren]

Here's a link to the process to read the TOD trouble codes:

http://www.vehicross.info/forums/sho...ight=TOD+codes

The other thing you might want to consider is to get some manual hubs to install on the front wheels, that way if your TOD acts up for any reason, it won't affect the driveability.

[Scott Larson]

It sounds like the transfer case control module is to blame but your code reader should confirm that...

[nfpgasmask]

I'm having TOD issues too. So far, I have changed the two speed sensors in the back of the xfer case. This did not fix it. Next I need to change the trans speed sensor under the shifter console.

I will be watching this thread. Get your codes read and start there.

Bart

[Scott Larson]

Just a suggestion, disconnect your battery for a few minutes and see if that resets the TOD contol module.

[evillecutter]

Just a suggestion, disconnect your battery for a few minutes and see if that resets the TOD contol module.

im learning to to this after just about any work i do on my vx - think about what cell phones looked like 13 years ago let alone computers - its like control alt delete for a vehicle

[Scott Larson]

EXACTLY, that little trick can sort out all kinds of bugs on all kinds of vehicles...ya just never know!

[nfpgasmask]

There is actually a specific procedure for clearing the TOD codes. Disconnecting the battery for a while does not purge the codes.

Bart

[Scott Larson]

Can't that be done with the right code reader, or is there a specific procedure you have to follow?

[nfpgasmask]

Can't that be done with the right code reader, or is there a specific procedure you have to follow?

Click the link to the procedure at the top of this thread. The TOD codes are on a separate system.

Bart

[Triathlete]

No solutions but glad to see you are still around WW. Didn't your dad have a nice VX also?

[RickOKC]

Hey WW, I have doubts that your VX is it REALLY going into true 4 LOW.

I'm kind of a noob, but I don't see how that could happen since that would require physically changing of the position of the secondary 4 HI / 4 LOW lever. My suspicion is that the torque is being sent erroneously from back to front due to a tire pressure / wheel size / faulty sensor / other issue.

But like I said - I'm a relative newbie with limited skillz. It may be possible that you're actually going into 4LOW, but I have the doubts I noted above. I hope more knowledgeable people will speak up if I'm completely wrong (my feelings sure won't be hurt if they speak up and tell me I'm just plain ol' wrong!)

Try the procedure listed in link in tom4bren's first message. You don't need anything fancier than a small piece of wire with hand twisted ends to make the jumper in the ODBII port.

[Scott Larson]

I believe there's an electrically operated clutch pack in the TOD transfer case and that is contolled by the TOD module, anybody have more info on this? This vehicle and it's intricacies is new to me too...

[tom4bren]

I think you're both right.

IIRC:

When in TOD (4H), an electric clutch pulses power to the front end to drive the wheels if slipping is sensed.

When in 4L, the transfer case mechanically locks in power to the front end as well as giving the gear reduction.

[LittleBeast]

This was happening to me as well when my CV's were binding. It is not going into 4 wheel low really more than likely but all the lights light up right?