Air leaking from ABS modulator valve

If the modulator valve leaks continuous when service is brake applied, replace it. Air is leaking by the vlave seat.

 

Put a good old non ABS valve on there good to go

 

I also have trouble with these modulator valves on my 1998 T800. In low traction situations like snow, it seems if one tire is spinning, the modulator wants to apply the brakes to the tires that have traction. The result is I can't go anywhere even if I chain up one axle. Most stupid idea ever.

1. Do I just call the KW parts counter and ask for a modulator valve from a pre ABS truck? We used to have a 1995 T600 I could use that VIN.
2. Will this non ABS modulator valve cause the truck ABS light to stay on? NYDOT will give me a ticket for that on a 1998 or newer truck.
3. Will the non ABS modulator valve cause the trailer ABS light to stay on?

 

The traction control system is working as designed in that the air system is applying the brake on the wheel that has lost traction to slow it down to regain traction. Unfortunately this usually doesn't help you get unstuck.In the end spinning and loss of traction with a loaded unit will eventually cause damage to driveline components, especially with as inexperienced driver that may be new to snow and ice or in getting stuck situations. Replacing modulator valves is not the answer.

If you find yourself getting stuck often where just the powerdevider alone is not enough to get out, consider adding lockers to your current truck or on your next truck purchase.

I have also seen on Paccar trucks an "off road"switch that can disable the abs and traction control systems temporarily during slow speeds. I would suggest getting with your dealer to see if maybe this can be added to your truck as an option to save you some frustration. I have not looked into this but do recall seeing it in trucks in the past. I do understand you know what your doing as a driver.

 

Yes the truck in question does have this toggle on the dash but it does nothing. I suppose I could have the dealer look into it but I don't really trust them

 

If your truck is equipped with bendix I would suggest giving them a call (1800AIRBRAKE) to see if they can offer any advice on the topic. Plus their software program is free to download to hook up and maybe make something work yourself. Maybe the switch is not responding or set up in the ECU correctly?

 

Good thought on the ECU, I'll check Powerspec to see if that parameter is turned off.

 

Switch has to be held for 3 sec or so then the traction light should turn on in the dash signifying the system is currently disabled.

 

been driving that truck 11 years and never seen that traction light come one but this afternoon I will try your test Thanks