ABS and Brake Lights On

[Skijhp]

The vehicle with the issues:
1998 Windstar 3.8L w/ >110k miles.

I hope this will help others in finding and correcting this problem. I just spent 2 days troubleshooting down to the master cylinder brake sensor and a 15A fuse. I used the internet to find all I could about fixing the cause of the lights, since the vehicle inspection depended on it. All discussions pointed towards bad sensors(s). Also, I didn't utilize Autozone and their free service of downloading the fault codes. Figured I could beat this problem using simple troubleshooting techniques (which I didn't heed the first law of: check power supply and fuses first).

Yesterday I checked all the wheel sensors and came up with the following results:

LR: 2.5K ohm, 1.6vac
RR: 2.5K ohm, 1.6vac
RF: 2.16K ohm, < .5vac
LF: 2.12K ohm, < .5vac

The front I could only spin so much due to the the drag created by the tranny. The rear spun by hand, average speed.

Today, I came up with a better way of checking them; which checks the whole harness, from sensor to ABS connector. I pulled the 24 pin connector on the ABS unit and connected 4 pair cable (20awg) to the respective pins and ran the cable to the inside of the van; and with the help of an assistant, checked voltages and freqs while in motion. If you attempt to duplicate, use the standard RS232 male connector pins (DB9/DB25) to connect to the ABS connector (makes it a whole lot easier than trying to stuff a bunch of stranded wires into a little hole). Use heat shrink or electrical tape around each pin, this will prevent shorting at the connector.

The pinouts, center tab at top. Pins 1 - 12 on Left, top to bottom (1 top, 12 bottom); 13 to 24 on right, top to bottom, (13 top, 24 bottom). There are index numbers on the side where the wires go into the connector; none on the mating side.

Color code is solid/trace colors
Rear/Right (high) pin 8 Pink/Black
Rear/Right (low) pin 20 Red/Black
Rear/Left (high) pin 9 Light Green/ Black
Rear/Left (low) pin 21 Light Green/ Red
Front/Right (high) pin 10 Yellow/Red
Front/Right (low) pin 22 Yellow/Black
Front/Left (high) pin 11 Tan/Orange
Front/Left (low) pin 23 Tan/Black


Results below were taken with connector removed from ABS, jumper from connector ran into passenger side cockpit and measured with a Fluke 87 DMM and Tektronix THS720P Oscope while driving 25mph. Coordination between driver and reader a must when recording the readings, otherwise multiple runs will have to be done to get rid of the speed vs voltage/freq anomalies.

Right Rear:
Multimeter: 2.0VAC (1st run), 2.1VAC (2nd run)
Oscope: 5Vpp @ 267Hz (1st), 5Vpp @ 252Hz (2nd)

Left Rear:
Multimeter: 1.9VAC (1st), 2.0VAC (2nd)
Oscope: 6Vpp @ 257Hz (1st), 5Vpp @ 253Hz (2nd)

Right Front:
Multimeter: 1.8VAC (1st), 1.6VAC (2nd)
Oscope: 3Vpp @ 257Hz (1st), 4Vpp @ 257Hz (2nd)

Left Front:
Multimeter: 2.5VAC (1st), 2.3VAC (2nd)
Oscope: 5Vpp @ 250Hz (1st), 6Vpp @ 240Hz (2nd)

Other things to check besides the wheel sensors:
Cruise Control Brake Sensor and Fuse 30 – the brake sensor is mounted at the forward most end of the Master Cylinder and its mounted upside down. Brake fluid leaks into the inside of the sensor and seeps out the cable, which will render the Cruise control inop and will cause a short in the system. This will open Fuse 30 (15A) and then cause both ABS and Brake lights to illuminate. The Cruise sensor runs about $16US with tax and can be found at the Ford dealer (NAPA doesn't carry it). The part number on the receipt: XW7Z*9G652*BA.

Don't always assume that the most expensive part had failed, it could be that $.50 fuse that blew instead. Luckily for me, NAPA didn't stock the Right Front sensor, otherwise I'd be a proud owner of a new (but not needed) wheel sensor.

Oh yeah, I also see symptoms of a blown intake and/or head gasket: loss of coolant, excessive steam from exhaust, the chugging effect when its started cold, check engine light always on, etc.
I haven't looked into this one yet, really don't feel like becoming one with the engine anytime soon. I have a good feeling that my next vehicle will NOT be a Ford.

Good Luck out there !!!

Ski

[bobinkski]

I had the ABS light on my 96,3.8 and I cleaned all 4 sensors and topped off the brake fluid too just above the max line.No more ABS light on and I believe that autozone can not scan ABS system do to a different code numbers. Good Luck...

[12Ounce]

Skijhp
Good work on reading those signals from wheel sensors. Thanks for the input.

Based on the postings of others, I would guess the coolant leak may well be the lower intake gasket/seals. Not a huge repair job .. but you need to take care of it before it leads to bigger problems.

[SamNovice]

I have '98. It was losing coolant with white smoke at 98K miles. I took it to a dealer and was told that the problem with '98 was likely the upper intake gasket rather than the lower gasket. They were right and it was fixed for $500. They also cleaned the EGR ports at the same time. It runs nicely now. But I am not very happy with Ford that they let this problem to continue for so long (since '95). Don't they ever learn that happy customers are repeat customers? I was pretty happy with the windstar and about to purchase a freestar until this problem showed up. I guess that I won't be having a freestar on my drive way anytime soon.