ABS Light please help!

[SwiftThunder]

Ok so get this I figured out how to trouble shoot the abs system to get an error code and it came up with 16 flashes which from my research means everything is ok.......Im lost here the system says it is ok but the light stays on. Also on my 1993 all it has is rabs which is rear anti lock brakes... How else can I test my truck before i dig in too deep?

[Blue Bowtie]

Just to clarify some previously posted information;

1. The speedometer is electronically driven, and the input source is a vehicle speed sensor (VSS) mounted to the transmission, not to the differential;
2. As previously, stated, the RABS sensor is located in the top of the axle housing, but there is probably sufficient space to remove the 10mm hex head screw and sensor without raising the vehicle - At least, that's how I've done it;
3. If the sensor is removed, make sure you clean the surrounding area before removal, and clean and oil or replace and oil the O-ring sealing the sensor to the housing;
4. As previously warned, the bolt may be corroded, so applying a penetrating oil may help ease removal. Just make sure the area is cleaned of dust, pebbles, mud, or other debris before removing the sensor.

The sensor should be unplugged from the harness and tested with an ohmmeter. A good sensor should present between a 800 and 2,000 ohms resistance. A brand new sensor is 1,800 ohms. Even if the sensor passes resistance test, you might want to remove it and clean any metal particles from it. The sensor uses a permanent magnet and inductive pickup coil to generate signal, and metal particles attracted by the magnet and stuck to the sensor face can interfere with good signal generation:




If the sensor coil passes the resistance test, and the sensor is clean, you can test the sensor output. Raise and securely support the vehicle. Connect a voltmeter on an AC scale to the sensor terminals. Spin the rear wheels at 3-5 MPH. The sensor should produce a 0.60VAC signal or greater. If not, the sensor may be bad or the tone ring in the differential housing may be damaged or filed with metal particles. That's what happened to this one:



You can use a stiff brush and solvent or spray-type carburetor cleaner to remove excessive metal buildup from the tone ring and restore good signal generation. Once the axle is cleaned and reassembled, you can test the signal generation once again.




If the output signal at the sensor is acceptable when tested directly at the axle, but the signal received by the EBCM is weak or faulty, disassemble and check the bulkhead electrical connector beneath the cab, directly under the drivers' seat. That's a poorly engineered location for a marginally sealed connector, and it is prone to moisture intrusion. Corrosion and moisture will not only affect the RABS sensor, but speedometer VSS signal as well, since they are both in that connector. In extreme cases, I've actually watched the speedometer indicated speed increase or decrease by 10 MPH whenever the brakes are applied, since the brake lamps are also routed through that connector.

Loosen the 10mm hex bolt and open the connector from beneath the truck. Clean it the connector pins and sockets, apply a water dispersant like WD-40, then blow it dry. Repair any corrosion on the contacts. Treat the perimeter seal with silicone dielectric grease and close it up.


One of those steps should either solve the problem or identify a weak sensor or damaged tone ring.

If you have a '93-99 truck, you can ground the black/orange wire near the park brake pedal with KOEO. Ground the wire for two seconds, unground the wire, then watch the ABS warning lamp strobe out the error codes. The first flash is usually a short flash, and the last flash is always a long flash. If the code is a "1" there will only be one, long flash. If the code is a "2' or numerically greater, all flashes will be short EXCEPT for the last flash. The last (long) flash is counted as part of the total, so by example, five shorts and one long would be interpreted as an error code "6."

Error Codes repeat continuously, and reporting will stop when the ignition is turned off.

If the truck is a 2000 or later, you'll need an ABS capable scanner to retrieve codes.

Error codes for Pre-2000 trucks are as follows: (2000-Up vehicles use standard OBD-II code protocols)

1 - Should Not Occur

2 - Open Isolate Solenoid Circuit

3 - Open Dump Solenoid Circuit

4 - RABS Valve Switch Closed - Should Also Cause Red BRAKE Warning Lamp to Turn on

5 - System Dump Cycle Too Frequent

6 - Intermittent Sensor Signal

7 - Isolate Solenoid Valve Test Failed

8 - Dump Solenoid Valve Test Failed

9 - Sensor Resistance High or Open Circuit

10 - Sensor Resistance Low or Shorted Circuit

11 - Stop Lamp Switch Circuit Defective

12 - Fluid Level Switch Grounded During RABS Stop

13 - Speed Processor Check

14 - Program Check

15 - System Memory Failure

16 - System Normal or Should Not Set Code


Good luck with your Ford/Mazda system.

[SwiftThunder]

Oh my god that is the help I have been looking for for a few weeks now. Thank you soooo Much I really appreciate the time you put into this. Im going to print this out and follow procedure. Hey one last thing well two when I am driving at slow speeds my speedo bounces around its not steady how can i fix that? Also half the lights in my instrument cluster are out do you know a place where I can find the lights online?? Thank you again If I have any more questions Ill try to contact you.

[Blue Bowtie]

The cluster can be accessed fairly easily. Be careful removing the cluster from the dash since there is very little extra wire connected to the rear side. You can either reach around and unplug the three electrical connectors and remove the entire cluster, or just reach around and remove the lamp holders and replace the lamps. Most well-stocked parts stores should have the lamps. I'm not sure about a '93, so don't quote me, but I believe the miniature wedge-base lamps you need are not the typical 194, but are either 24, 37, or 74 lamps. Find someone who supplies those and you should be all set once you get the cluster out.

As for the speedometer itself, if the VSS signal is consistent but the speedo does not operate smoothly, that's merely a nuisance. However, if the VSS signal is intermittent, it may not only be affecting the speedometer but could be a primary reason the ABS warning lamp keeps turning on. If the RABS sensor does not agree with the VSS input, the system can interpret that as a lockup or RABS sensor problem.

[SwiftThunder]

Ok so last night I took out the cluster and it was difficult to remove at first because it not only has two harnesses but the speedo is not electronic it is one of the old school ones that has a revolving shaft in a cable that was hard for me to figure out since my t-bird is electronic, so I just determined that it wont be that smooth of a speedo due to its age. And the lights in the cluster were 194 wedges and since I didnt have any money I used the lights in the cluster that werent uses such as 4x4 etc and moved them around it works now its nice and bright and clean. Thank you again for all your help.

[butch h]

You can pull the inner cable out and lubricate it with white grease, that shoul d calm it down.

[SwiftThunder]

So it turns out that after all this help it was a $12.00 fix with a sensor from autozone. So thanks for all your support.

[Blue Bowtie]

Cool! It's usually just one part that can mess up the whole system. Finding the information to diagnose the part is where we come in.

FWIW, if you are going to pull the speedo cable to lubricate it, clean it first, then apply graphite powder instead of grease. The grease will actually work just as well, until the first cool winter morning when it is about as viscous as frozen honey. Then you can experience the same kind of problems you do now, or worse, snap the cable.