Brake bleed question

[mkcustoms881]

Ok thank you

 

[AuroraGirl]

If you're a cheapass, you may be able to get away with cycling ABS on a dirt road vs using a tech 2. I feel that probably works better for an old dirty fluid purge than an air purge, but still worth a shot. Or delete the infernal thing like I did on my 1500. I wonder if OP has air in the master now as well?

are you sure a tech 2 has a bleed function on a truck from this time? I had my tech 2 on my 96 and I dont recall seeing chassis functions, but its been a long time. I remember it being simplistic compared to my car for sure but i could just be remembered wrong.

I would think something like RABS has a bleed valve on the unit and just requires that done in a certain step compared to the rear drums, but that could be the f150 in my life bleeding into my gm side here

 

[AuroraGirl]

Also if the rear lines were broken, id ask if these trucks have / use a residual pressure valve on the master cylidner outlet to the rear to maintain 10 ish PSI on the rear shoes so that when the brakes are applied the system doesnt have to overcome the springs before braking(thus starting to brake at the same time as the front)

if they do, I would make sure its not gunked up or just replace it since nasty fluid + open to the air may have corroded it and that wouldnt be very fun with intermittent operation of the rear brakes(properly) in relation to the front

 

[Supercharged111]

are you sure a tech 2 has a bleed function on a truck from this time? I had my tech 2 on my 96 and I dont recall seeing chassis functions, but its been a long time. I remember it being simplistic compared to my car for sure but i could just be remembered wrong.

I would think something like RABS has a bleed valve on the unit and just requires that done in a certain step compared to the rear drums, but that could be the f150 in my life bleeding into my gm side here

Not sure what we're calling the function, but the tech 2 is supposed to be able to cycle the ABS pump and valves. From my understanding, you need to do this more than once if you're getting air out of the ABS pump as it is not a bleed function like on the simpler RWAL setup.

 

[AuroraGirl]

Not sure what we're calling the function, but the tech 2 is supposed to be able to cycle the ABS pump and valves. From my understanding, you need to do this more than once if you're getting air out of the ABS pump as it is not a bleed function like on the simpler RWAL setup.

Is the truck in question have a traditional ABS setup and not a RABS anti skid setup? I guess I am possibly mistaken what you are talking about for this

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is this what you are referring too?

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Which now posting that I see the diagram up above referenced this too

I guess I didnt realize the system was vastly different in how it looked between ford and GM

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This is fords valve and that itself is bled like a wheel brake cylinder/caliper at a certain point I believe before the rear brakes. The GM one is at the same level as the master, and it looks to have better behavior when in use, I guess its funny because the system is the "same" base Kelsey Hayes system, strange. Wonder if it has to do with how ford uses their bendix brake systems vs gm uses their (delphi?) with regards to proportioning, rear drum setup.. etc.. I would say gm's is better just because Id rather do a GM drum brake before another ford drum brake in my life but lol.

Based on the big kahuna of a electronic module on top the system I would say the GM one having a automated scan tool process to cycle the unit to bleed air out of it sounds about right. Fords had memory for a single trouble code, it was often lost with key off because of course it was, and their valves didnt like to stay working after time ever usually.

 

[AuroraGirl]

Not sure what we're calling the function, but the tech 2 is supposed to be able to cycle the ABS pump and valves. From my understanding, you need to do this more than once if you're getting air out of the ABS pump as it is not a bleed function like on the simpler RWAL setup.

Chassis functions would be things like changing air ride heights, wheel sizes, bleeding brake systems(usually ABS), calibrating stability systems, changing steering effort(trucks had EVO but cars had magnasteer, that is what I mean), etc. The wheel size is the only thing I remmeber seeing but I would not be surprised with the RAWL thing

 

[delta_p]

I have used my tech2 to cycle the ABS pump and valves on my '96 C1500. This is just a function test though, that's why you run it several times.
Chassis>4WAL 3 Sensor>Special Functions>Function Test

On a '98 it looks like there are more option than just running function test,
Automated Bleed
ABS motor
Solenoid test
ABS relay

The '98 routines won't run on a '96.

 

[Nad_Yvalhosert]

The '98 routines won't run on a '96.

If like to know how to ABS bleed a '95. 4 wheel ABS, but OBD1. Any suggestions?

 

[Supercharged111]

If like to know how to ABS bleed a '95. 4 wheel ABS, but OBD1. Any suggestions?

Is that a 3 channel or 4 channel? I know my 97 and 98 have 3 channel.

 

[Nad_Yvalhosert]

3. Same as yours

Same as my '00 Denali for that matter