1998 SVT ABS Brake problem (Happened to mine)
Posted 20 December 2002 - 02:57 AM
Anyhow - Since winter is here I started having some strange problems. First off the ABS brakes would work for about 2-3 seconds and then make a loud sawing noise and the brake pedal would go to the floor (consequently causing all 4 wheels to lockup and an interesting 180 degree spin). The first time it happened I thought for sure the brake system itself was boned up. So I inspected everything (lines, calipers, pads..... even the power and grounds into the ABS unit) all checked ok. So I performed a brake fluid flush and found some rust in the rear caliper fluid and also the fluid had a dark green tint to it. So I changed the fluid and bled all 4 wheels according to the manual. This didn't seem to help at all. I then drove the car to a local Ford dealership and explained my problem ( and also had them do a NGS Bleed on the ABS system just in case I missed some trapped air in the ABS Hydraulic pump ). They said they found alot of air inside the ABS pump assy and the ABS was functioning fine. Well, not even a day later I was faced with an opportunity that I had to depend on my ABS to help out with and it did the same thing (ABS worked for a couple of seconds, lights dimmed and the pedal made a sawing noise and went to the floor - locking all 4 wheels and causing the car to slide sideways). This severely pissed me off, and after calling the Ford dealership they told me that they hadn't had any problems with the ABS units and that possibly there was something in the brake system that was preventing the ABS unit from properly doing it's job.
Hearing that they hadn't encountered any problems made me curious - So I headed over to the NHTSA.Com website and browsed all the customer defect complaints on 1998 Contour models. 28 complaints total for brake failures, over half are ABS concerns where the wheels locked up and loss of control was reported. For grins and giggles I searched 1999 models for the same problem and guess what? Not a single report of an ABS problem. Hmm... what changed?
As you can already guess starting in 1998.5 Ford switched to a new ABS pump/hydraulic unit. The Mecatronic 3 unit was phased out for the lighter (and more reliable) Bosch 5.3 unit. Shown in the pic above is what the unit entails including the brake lines. Feeling the Bosch unit over the Mecatronic was night and day. The Bosch unit was approximately half the weight of the old unit and has a smaller footprint underhood. Now, most of you have never seen your ABS unit or where it's located, the location is on the drivers side firewall under the Brake Booster unit. Now to gain access to the pump you will need to remove the master cylinder and brake booster. The booster isn't that much fun to remove ( I've had plenty of experience in getting the booster out before on other cars so I had a slight edge in getting mine out..) Here's a pic of the old ABS unit removed, and a pic of it on the ground.
It's a fat and wide unit - Weighs around 12 lbs. It has 6 lines going in, 2 from the Master Cylinder(feed) and 4 output lines. The connector on the old unit cannot be used on the new unit. It has a two row connector vs. the three row used on the Bosch unit. Here's the difference:
Mecatronic 3 connector (Factory equipment)
New Bosch 5.3 connector (Factory harness)
This meant that I had to splice the harness to make this work. Luckily the ABS speed sensor wires are all the same colors so that is easy. The only real hurdle is the power/ground and ABS light. The ABS light does not work the same in the 98.5 cars then they do in the 1998 cars. I still have to re-wire mine, but I don't care to see the ABS light as long as I know it works :)
Installation is pretty straightforward as long as you have all the brake lines coming off of the unit. I lucked out and found a unit (Thanks Matt) that has everything intact. Suprisingly it did bolt right in without too much drama. The wiring wasn't that bad as I had a copy of the diagrams for both units sitting in front of me. Before and after installation pics here:
Yes, it can be pretty un-nerving and also extremely difficult for the normal joe. I'm not the normal joe and I've never had it easy :) so I'm used to it. Trust me, replacing the ABS unit is far more simple than replacing the alternator on a 2.5 ...
After all the installation was complete, the booster and master cylinder re-installed and lines secured - I bled the system to purge all the air in the lines and took it out for a test to see how effective it was. It was a night and day difference in ABS performance over the old unit it replaced. The ABS on my car never worked that great from the beginning and this unit is incredible for how it modulates the pressure to keep the car straight. Anyone who is in the same situation with their 1998 SVT ABS system malfunctioning I would HIGHLY suggest instead of replacing it with a new/used Mecatronic unit to convert to the newer Bosch system and feel the difference in the performance.
At least now I can drive without worrying about sliding/losing control in a panic stop. That in itself is worth the conversion.
P.S. If anyone is interested I can help with wiring diagrams and also tips on installation - Just email for details.
Posted 20 December 2002 - 03:05 AM
Posted 22 December 2002 - 02:02 AM
opt to replace the original unit with the Bosch unit if they did determine the problem to be the ABS or would they just replace it with
another "old style" unit?
Posted 22 December 2002 - 02:56 AM
Posted 22 December 2002 - 11:52 AM
Posted 22 December 2002 - 01:54 PM
Posted 04 January 2010 - 11:32 PM
Posted 05 January 2010 - 07:34 AM
Posted 24 January 2010 - 11:41 AM
Posted 24 January 2010 - 08:20 PM
Aside from the ABS unit and the matching harness no other relays or parts are needed.
Lol... on second thought. Did you try to bypass the brake light switch input by switching it to positive feed? You must run a seperate wire inside to the brake pedal switch for activation otherwise it will stay on all the time..!! Perhaps that's the malfunction???
Posted 25 January 2010 - 04:33 AM
Posted 25 January 2010 - 10:44 AM
I have documented the wiring that i did on the other forum...
ABS swap - mecatronic to bosch - CEG Forums
So looks like the orange/green wire from port 6 on the bosch connector needs to connect to the brake pedal.
Is it pretty self explanatory as to how to connect the wire to the brake pedal switch?
is this the wire? From the schematic it looks like its a ground wire that is completed with the brake switch.
Edited by matthewsgordone, 25 January 2010 - 10:50 AM.
Posted 25 January 2010 - 11:35 AM
Posted 25 January 2010 - 12:35 PM
..I don't think that is a ground circuit with a fuse in it...
I was under the impression that dashed lines where grounds, but i thought the fuse in it was kind of weird...
Posted 25 January 2010 - 12:45 PM
Posted 25 January 2010 - 01:02 PM
The orange/green wire must to be connected to the output of the brake lamp switch (hot when the pedal is depressed).
P.S. I copied your diagram off of CEG - I'll look it over with what I have and post later when I get off of work.
Posted 25 January 2010 - 02:33 PM
'Other circuits are also grounded at GXXX but are not shown can also be referenced in Ground Distribution...'
...and also ' 'A thick dashed line represents 2 or more wires...'
Posted 25 January 2010 - 09:33 PM
New connector wiring
Pin #1 : Empty
Pin #2 : RR+ Speed Input - Old Pin #9
Pin #3 : RR- Speed Input - Old Pin #10
Pin #4 : RF+ Speed Input - Old Pin #7
Pin #5 : RF- Speed Input - Old Pin #8
Pin #6 : Stoplamp circuit (Must run wire to stoplight switch (Orange/Yellow) wire).
Pin #7 : Not Used
Pin #8 : F7 BJB 10A Power Input - Old Pin #5
Pin #9 : Not Used
Pin #10 : Not Used
Pin #11 : Not Used
Pin #12 : Ground - Old Pin #1
Pin #13 : Power 12V (Shared with Pin 14) - Old Pin #3
Pin #14 : Power 12V (Shared with Pin 13) from 60A F3 BJB - Old Pin #3
Pin #15 : Ground - Old Pin #2
Pin #16 : BK/BU Park Brake/Low Fluid Level ground input (Optional)
Pin #17 : Not Used unless equipped with Traction Assist
Pin #18 : Not Used unless equipped with Traction Assist
Pin #19 : Not Used
Pin #20 : LF+ Speed Input - Old Pin #21
Pin #21 : LF- Speed Input - Old Pin #22
Pin #22 : LR+ Speed Input - Old Pin #23
Pin #23 : LR- Speed Input - Old Pin #24
Pin #24 : DLC ( Direct to DLC - No PCM) - Old Pin #11
Pin #25 : ABS Indicator (With older cluster will cause ABS light to stay on permanently) - Old Pin #20 if you want an idiot light on all the time.
Pin #26 : Not Used
Pin #27 : Not Used
Pin #28 : Not Used
Pin #29 : DLC - Through PCM - Can't be used with 1998 RJL1 PCM
Pin #30 : DLC - Through PCM - Can't be used with 1998 RJL1 PCM
Posted 23 February 2011 - 07:57 PM
Posted 28 April 2011 - 11:27 PM