"ABS anti lock"

[Hellbillie]

Hi
94 - 6,5TD
In the morning, or when stopped for some hours, the "ABS anti lock" warning light comes on right after starting to move. Stays on, but dissapear if engine is stopped and restarted.
No codes, only dash warning light.
Bleed wheel lines couple of times. Problem started whitout any brake job done.
Some times when warning light is on, tranny also act strange. Seems to have problem shifting up.(Much higher rpm. than normal before shifting)
Tranny acting normal as soon as ABS warning light is off.

Anyone who know where to start looking?

[ECMProgrammer]

With 'any' check engine light or ABS light, the first thing to do is get the trouble codes with an appropriate scan tool...and diagnose from there.

Lyndon
www.ecmprogrammer.com
Westers Garage
1-888-WESTER-1

[Hellbillie]

Hi Lyndon
You are right, and today tranny was acting funny whitout any ABS failure.
Checked if there are any codes, and now code 72 was present. According to the manual, this indicates VSS loop malfunction.

From what I can see in the manual, VSS sensor is used by both transmission and ABS module. If this is the case, my problems could be a faulty VSS sensor.

Comments?

[Robyn]

If memory serves, there are two sensors.
one for the input speed and one for the output speed of the tranny.

The VSSB could also play into this equation.

The ABS fault light lends me to believe the output shaft sensor is getting hinky.

This sensor feeds info to the ABS as well as the tranny.

If the computer sees a strange anomally between the front and rear wheel speeds it can trip the code.

Having an issue with the sensor also will cause the tranny to shift wierd too.

Very good bet the output shaft sensor is bad.

Good luck and let us know

Robyn

[Hellbillie]

I`ve checked tranny for sensors, and one sensor is located on left side of the tranny itself. I suppose this is the "input speed sensor". There is a slot for one more sensor in the tranny, but here is no contact or wiring. Seems that it never has been connected. According to an article I found, there should be two sensors, and they are referred to as "input speed sensor" and "output speed sensor". If this is right, I don`t have "output speed sensor"??? (Both of these sensors are fixed to the tranny with a small clip and a srew).

On the output shaft from the tranny, there is one more sensor, wich I belive is the "output shaft sensor". (This one is a little bigger that the other one, and has outside threads for mounting)

When removing contact from "output shaft sensor", I lost the speed reading and tranny would not shift at all.

I belive you are right in your assumptions robyn, so I`ve ordered a new "output shaft sensor", and just in case I`ve also ordered a new "input speeed sensor" (If my presumption is correct)

Let you know the result when I receive the sensors, and thanks again

[Robyn]

Lets hope this does the trick.

I am assuming you have a 4x4 ?? the output sensor will be on the back of the T Case and not the tranny. The spot on the tranny will be plugged.

Good luck

Robyn

[Hellbillie]

Hi again

Right Robyn, sensor is located on the back of T case, and I`m having a 4x4.

New output speed sensor arrived, and changed.
All problems related to strange tranny behavier and ABS warning light gone.

Thanks for all help.

Regards
Hellbillie.