New owner with a question about ABS/Brakes

vtmach1

New Member
Nov 7, 2020
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27
Texas
Howdy all! New owner with a question about ABS/Brakes. Bought the car recently with the ABS light on and figured I could diagnose it. Doing some work on the car today and I noticed that my booster/master cylinder are wet and possibly leaking fluid down onto the front k-member. I've only ever done pads/calipers/rotors, so I don't know much about messing with master cylinders/boosters/abs modules. I tested the wheel speed sensors and they all came back within the acceptable range as well as continuity testing the harness. I'm assuming the leaking components are my culprit since I cant seem to pull codes from the obd2 port. My question is do I need to replace both the booster and master cylinder, or is there a way I can tell which one is bad?
 
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7991LXnSHO

Now I want a 10 year badge
10 Year Member
Sep 1, 2010
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This is addressing a need other than your question. If you OBD 2 port is not communicating, it makes fixing at least the brakes, airbags and engine problem more difficult. Here is what I have found out for multi brand fixes, and someone may have Stang specific directions.
Check all your fuses.
Make sure there is power to the lighter (it’s often on the same circuit as power to the port.)
Check the wiring to the port.
Make sure the port is not full of foreign matter.
There are diagrams on what power or signal should be at each pin location. If that checks out, the next step involves unplugging all the modules that report to the computer until it communicates.
after that, chasing wires, reprogramming the ECU or pushing it off a cliff might be the next steps.
Brakes are easy and someone SN 95 specific can help more.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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Massachusetts
If this is a GT, it has hydroboost. The power steering pump supplies fluid to the booster to use that for assist. It’s entirely possible the fluid you are seeing is power steering fluid leaking from the hydroboost, vs brake fluid. Brake fluid is rather aggressive on paint, so a sustained leak would have lifted the paint in the bay.

ABS codes are not transmitted like a generic obd2 code. You need a reader to pull them.

with Ford, I use Forscan and an ELM327 connected to my laptop. You can do a lot more with it than you could any code reader available to a consumer

www.forscan.org
 

7991LXnSHO

Now I want a 10 year badge
10 Year Member
Sep 1, 2010
3,593
812
174
Kearney, NE
If this is a GT, it has hydroboost. The power steering pump supplies fluid to the booster to use that for assist. It’s entirely possible the fluid you are seeing is power steering fluid leaking from the hydroboost, vs brake fluid. Brake fluid is rather aggressive on paint, so a sustained leak would have lifted the paint in the bay.

ABS codes are not transmitted like a generic obd2 code. You need a reader to pull them.

with Ford, I use Forscan and an ELM327 connected to my laptop. You can do a lot more with it than you could any code reader available to a consumer

www.forscan.org
That’s cheap for good software!
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,673
10,838
224
Massachusetts
That’s cheap for good software!

it really does a lot. You can program modules, and changes some features in the as built data. The latter applies to later fords mostly but I used it to turn on my oem navigation, and change the number of blinks when I half press the stalk from 3 to 5, or disable the double honk if I get out of the car with engine running. It also can pull DTSs from all the various modules. Free software and an excellent support forum
 

7991LXnSHO

Now I want a 10 year badge
10 Year Member
Sep 1, 2010
3,593
812
174
Kearney, NE
it really does a lot. You can program modules, and changes some features in the as built data. The latter applies to later fords mostly but I used it to turn on my oem navigation, and change the number of blinks when I half press the stalk from 3 to 5, or disable the double honk if I get out of the car with engine running. It also can pull DTSs from all the various modules. Free software and an excellent support forum
I’d be glad to pay for the extended license if I was going to be using it. The VAG-COM we need for an import (Beetle) gets expensive fast.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
34,673
10,838
224
Massachusetts
Ouch. Yeah I’ve heard of Vag-com but never used it. I do the 3 month free license on ForScan when I need it.

other than Forscan and vag-com I don’t think there is any other available software for other makes
 

vtmach1

New Member
Nov 7, 2020
3
0
1
27
Texas
Wow, lots of good info.

This is addressing a need other than your question. If you OBD 2 port is not communicating, it makes fixing at least the brakes, airbags and engine problem more difficult. Here is what I have found out for multi brand fixes, and someone may have Stang specific directions.
Check all your fuses.
Make sure there is power to the lighter (it’s often on the same circuit as power to the port.)
Check the wiring to the port.
Make sure the port is not full of foreign matter.
There are diagrams on what power or signal should be at each pin location. If that checks out, the next step involves unplugging all the modules that report to the computer until it communicates.
after that, chasing wires, reprogramming the ECU or pushing it off a cliff might be the next steps.
Brakes are easy and someone SN 95 specific can help more.
Fuses are good, that was the first thing I checked. It is missing the 12v outlet/cig lighter by the shifter, if that's what you're referring to. and what do you mean by "port"? I ohm checked the wheel speed sensors and continuity checked the connectors and everything came back a-ok.

If this is a GT, it has hydroboost. The power steering pump supplies fluid to the booster to use that for assist. It’s entirely possible the fluid you are seeing is power steering fluid leaking from the hydroboost, vs brake fluid. Brake fluid is rather aggressive on paint, so a sustained leak would have lifted the paint in the bay.

ABS codes are not transmitted like a generic obd2 code. You need a reader to pull them.

with Ford, I use Forscan and an ELM327 connected to my laptop. You can do a lot more with it than you could any code reader available to a consumer

www.forscan.org

It is leaking onto the k member and in the bay, but no paint gone yet so you might have a point there. no loss in brake pressure from what i can tell. Car still does 60-0 pretty quickly, just no abs lockup (that I've noticed). Ill check out Forscan though. I've tried connecting with hptuners with no luck so far to pull codes/view other diagnostic info. might be a software issue on my end though
 

vtmach1

New Member
Nov 7, 2020
3
0
1
27
Texas
Well, I think I figured it out....

PO had two different sized tires on the rear (275/35 and 275/40). While I knew I was going to have to replace these with same sized tires since the rear diff clutches are toast now, i finally put 2 and 2 together and realized that they must be triggering the abs (but not the traction control for some reason). Occam's Razor in action.