Will 4x4 Work With ABS INOP

c_johnsen · Jan 3, 2022

I recently received a 2004 Expendition I’m using as a farm vehicle. It needed brakes but I was told 4x4 worked when I got it (I did not confirm).

Since it’s never used on the road I blocked off the rear brakes, and tees off the master cylinder to each front wheel bypassing the ABS (I took out the ABS pump).

when I try to engage 4x4 the light flashes on the dash for 10 seconds or so but never engages. So will 4x4 work with the ABS bypassed. Or do I have a different issue?

If the 4x4 indeed won’t work without ABS is there any way I can manually get it in 4x4. The car never goes over 15mph or so and 4x4 is pretty important.

tommyddsr · Jan 3, 2022

Is there a reason you didn't just fix the brakes? Sounds like you are just creating more work for yourself. ABS is tied into many safety systems but I am not sure about 4x4 engagement.

c_johnsen · Jan 3, 2022

I got the car for free. It will never see another paved road or be registered in its life. It it just used to carry materials and supplies to the house. Never going over 10-15mph.

If I can’t get 4x4 working on this I’ll just look for another free car to use. I’m not going to spend the time and money to run all new brake lines and get a new ABS pump. I would love to get the 4x4 on this working because it’s it in really good shape.

tommyddsr · Jan 3, 2022

So when you said it needed brakes you meant the brake system was shot. Makes more sense now.

c_johnsen · Jan 3, 2022

Sorry I should have been more specific. When I got it it had 3 frozen calipers, 2 rotted rubber brake lines, and needed all new steel lines. Since it’s never going on the road again I blocked off the rear brakes at the master cylinder and put new calipers, rubber hoses and steel lines across the front.

My local part store didn’t have the bubble flare fittings to do everything in metric so I got a few adaptors and double flared the lines. Therefor I couldn’t use the ABS pump so I less than gently ripped it out and threw it in the scrap pile. Plus it gave me a little extra room to get the steel lines in.

Now the 4x4 won’t engage. I was told it worked when I got the vehicle but never tested it myself. So I’m wondering if it won’t go into 4x4 because of the lack of ABS or if the motor on the transfer case is shot. Trying to do a little research before I start throwing money at it (which I’m trying to avoid). Thanks

mbtech2003 · Jan 9, 2022

Mine had abs light on. 4x4 works fine. A4WD does not function

mbtech2003 · Jan 9, 2022

c_johnsen said:
Sorry I should have been more specific. When I got it it had 3 frozen calipers, 2 rotted rubber brake lines, and needed all new steel lines. Since it’s never going on the road again I blocked off the rear brakes at the master cylinder and put new calipers, rubber hoses and steel lines across the front.

My local part store didn’t have the bubble flare fittings to do everything in metric so I got a few adaptors and double flared the lines. Therefor I couldn’t use the ABS pump so I less than gently ripped it out and threw it in the scrap pile. Plus it gave me a little extra room to get the steel lines in.

Now the 4x4 won’t engage. I was told it worked when I got the vehicle but never tested it myself. So I’m wondering if it won’t go into 4x4 because of the lack of ABS or if the motor on the transfer case is shot. Trying to do a little research before I start throwing money at it (which I’m trying to avoid). Thanks

Just saw this part. I believe The 4x4 requires communication with the abs module to function. So removing the module rendered it non functional.

Uberexpy · Jan 11, 2022

Yes, I found out the auto4wd needs abs speed signals.

whtbronco · Jan 11, 2022

It appears the ABS system is required for 4wd, stupid in my opinion. Man I miss the reliable old manual shift transfer cases.

The automatic 4-wheel drive transfer case system consists of the following:

automatic 4WD indicator light
Brake Pedal Position (BPP) switch
Integrated Wheel Ends (IWE) solenoid
Torque On Demand (TOD) relay
4WD control module
4WD high indicator light
4WD low indicator light
4WD Mode Select Switch (MSS)
shift position sensor
Throttle Position Output (TPO) from the Powertrain Control Module (PCM)
transmission range sensor
average front and rear wheel speed signals from the anti-lock brake system.

That said since it sounds like leaving it 4wd might be acceptable in your situation I wonder if you could pull the shift motor and manually shift it. By unplugging the wheel hub vacuum solenoid the hubs should remain locked/engaged since they engage when vacuum is not present.

Underdog66 · Jan 15, 2022

whtbronco said:
It appears the ABS system is required for 4wd, stupid in my opinion. Man I miss the reliable old manual shift transfer cases.

The automatic 4-wheel drive transfer case system consists of the following:

automatic 4WD indicator light

Brake Pedal Position (BPP) switch

Integrated Wheel Ends (IWE) solenoid

Torque On Demand (TOD) relay

4WD control module

4WD high indicator light

4WD low indicator light

4WD Mode Select Switch (MSS)

shift position sensor

Throttle Position Output (TPO) from the Powertrain Control Module (PCM)

transmission range sensor

average front and rear wheel speed signals from the anti-lock brake system.

That said since it sounds like leaving it 4wd might be acceptable in your situation I wonder if you could pull the shift motor and manually shift it. By unplugging the wheel hub vacuum solenoid the hubs should remain locked/engaged since they engage when vacuum is not present.

Very odd. My 2005 has the ABS light and the AdvacTrac light both on, as well as a warning in the information center stating the AdvacTrac is malfunctioning. Both AWD and 4WD work. The ABS doesn't work though. I have been trying to track my issue down to no avail. I'm actually writing a post about my issue.

Will 4x4 Work With ABS INOP

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