1992 Ford Thunder bird SC with ABS Break booster or Master Cylinder?

The ABS system on your car was called the TEVES MkII which was an all integrated system. What that means to us is that our system contains all the controlling hydraulic components into one unit called the Hydraulic Actuator Assembly. The Ford service manual has over 100 pgs. dealing just with the diagnosing and trobleshooting of the ABS system so anything involving this system is very expensive to have worked on and is not something that the average shop has the ability to work on much less repair.

I examined the FORD Electrical & Vacuum Troubleshooting Manual for the 89 through 92 model years. The electrical system for the ABS System was virtually identical between all model years. Lets describe what happens to power this system.

When the ignition key is placed into the start or run position, power is applied to a portion of the ABS Control Module (Electronic Controller) via the 10A CLUSTER Fuse. The ABS Control Module applies power to the Anti-Lock Power Relay when the Ignition Switch is placed into the START Position. This relay closes it's contacts allowing power to flow from the ABS MOD 30A Fuse in the Primary Distribution Box (inside the engine compartment) to the rest of the ABS Control Module. This relay is a "seal-in relay" in that it continues to be closed even when the Ignition Switch is released to the run position. The purpose for this relay is that it allows a relatively large amperage load to be powered but not directly from the ignition switch. This way up to 30A of power can be supplied to the system without relying on the contacts in the ignition switch to do it. After the system is energized it performs a self test. If you place your ignition switch to the run position without starting the car you can watch this test being run. This self test will check electrical continuity of the system as well as the Electronic Controller for proper operation. The Amber Anti-Lock light will illuminate for approximately 4 seconds and then extinguish if all is well with your system. If you then place the switch to the start position and start your car you should see the following cycling of lights. The Amber Anti-Lock and Red Brake Light should illuminate. The Hydraulic Pump Motor most likely will run since the pressure sensed by the Pressure Switch in the system is probably low (below 2030 PSI)if the car has been sitting a while. The Pressure Switch will allow power from the ANTI LOCK 10A Fuse to cause the Hydraulic Pump Motor Relay to close it's contacts allowing power to flow to the pump motor from the ABS MTR 40 A fuse. It will also cause the Anti-Lock Warning Light to be illuminated. The pump running will pressurize the hydraulic accumulator to around 2650 PSI at which point the pressure switch contacts will open, the Hydraulic Pump Motor Relay will drop out and the pump will stop as well as the red and amber lights will extinguish. For all applicable model years the Anti-Lock Power Relay and the Hydraulic Pump Motor Relay are located on the passenger side firewall area. When facing the engine bay these relays are located as follows:

92 Model Year (Left to Right) Hydraulic Pump Motor Relay, Anti-Lock Power Relay, WOT AC Cutout Relay.

Note: This information based on diagrams in the Ford EVTM's for the appropriate year. If it is wrong, blame FORD not me.

The CLUSTER and ANTI LOCK fuses are located in the Primary Junction Box in the passenger compartment and the ABS MOD and ABS MTR fuses in the Power Distribution Box in the engine compartment.

Basic Troubleshooting

Most of the problems associated with this system seem to revolve around the electrical operation of the Hydraulic Pump Motor and the Accumulator. So lets describe what some of the common symptoms are and what you can do about it.

Hard pedal Amber Anti Lock and Red Brake Light always on.

• The hard pedal is indication of no power assist which we now knows means the Accumulator is not pressurized or the hydraulic pump is not running to pressurize the system. You should also realize that you don't have ANY rear brakes too. Run the Self Test and see the Amber Warning Light goes out in 4 seconds. Have an assistant stand by the open hood to listen for the Hydraulic Pump Motor to run when you start the car.
• If the pump runs, most likely you have a bad Accumulator or the pump is not being supplied with fluid because sediment has plugged the low pressure hose leading from the reservoir. Check the hose is unplugged and if that doesn't correct the problem replace the Accumulator. If this doesn't fix your problem you are into a high buck Pump Assembly replacement. (You already replaced the Accumulator so don't buy another one now). For reference you should be able to press on the brake pedal from 5-8 times without the Hydraulic Pump Motor running. If this is not that case you are due for an Accumulator soon.
• If the pump does not run you now most likely have an external electrical problem although it is possible the pump motor is shot. Here is how to tell what is what. With the Ignition Switch off depress the brake pedal 20 times to ensure the system is fully depressurized. Turn the Ignition Switch to Run the pump should run. If not disconnect the 4 pin connector on the pump. Use a multi meter to measure the voltage on the pins of the harness connector. The two positive pins are on opposite side of the connector as are the negative pins. Measure from one positive to one negative pin. (See figure 3).You should measure more than `10V DC. If you don't, potential problems include either the Hydraulic Pump Motor Relay, The Pressure Switch or the wiring harness between them all.

Figure 3 Four Pin Motor Connector

Figure 4 Hydraulic Pump Motor Relay Schematic and Pin-out

The failure of the Hydraulic Pump Motor Relay is a common occurrence. The normal failure modes are the contacts welded themselves shut causing the Hydraulic Pump Motor to run continuous or the relay failing to close which prevents normal pump motor operation. To verify relay operation it would be possible to disconnect the harness connector to the Anti-Lock Pressure Switch and ground pin 4 of the connector to ground.(See Figure 5) This will complete the circuit for the coil of the Hydraulic Pump Motor Relay and should cause the pump to turn on. If the pump does not run most likely the relay is bad and must be replaced. If the motor does run the Pressure Switch may be the faulty part and should be replaced. The FORD Shop Manual states that if the Pressure Switch is replaced the Hydraulic Pump Motor Relay should be replaced as well.

Anti-Lock Warning Light and Red Brake Light come on after brakes applied.

• Most likely this is indication of a weak or bad Accumulator. If you have this symptom it is important to fix it as soon as you can because you are cycling the Hydraulic Pump Motor unnecessarily which will cause this high buck part to fail sooner than it needs to.

Red Brake Light comes on when accelerating or braking or going around a corner hard.

• Probably your brake fluid level is a tad low. Angles and dangles on the car are causing it to pick up the level sensor. Make sure your system is pressurized when you check / add fluid since the Accumulator will "store" an appreciable amount of fluid. This will cause the level to go down as the system is pressurized at start up. Where did the fluid go you might ask? Assuming you have no leaks it probably is as a result of the brake pads in your calipers wearing. As they wear more fluid is required to keep the caliper pistons maintained in the proper position for braking action.

Figure 5 Anti-Lock Pressure Switch Pin-out

Other Problems that might be troubleshot by the DIY

Just like the EEC the ABS System has a Test Connector which may be used to download error codes from the ABS Electronic Controller. It is located on the right rear quarter panel trunk area. The types of codes present here will be basic system faults which will cause the Amber Anti-Lock Warning Light to remain lit even after 4 seconds have elapsed on the Self-Test. As far as I know, any aftermarket Code Reader that is compatible with the FORD EEC System can be used to access these signals. Two things to be aware of though. One, if the first code received is in the 20's, service the indicated fault. No other codes can be outputted to the code reader if a 20's fault exists. After servicing the 20's code repeat getting codes from the Electronic Controller. Two, the memory can be cleared only by reading all codes present, all faults being corrected (anti-lock warning light off) and the vehicle being driven above 25 MPH.

The troubleshooting techniques used for these type of problems are more involved than what is commonly used, but I have included the Service Codes for those of you that are more adventurous. I have tried to give a short summary of what checks are made but if it is not something obvious you are going to have to get the manual or visit a dealer unfortunately. I included this to give you a direction to look for the obvious rather than becoming an ABS Expert Troubleshooter. There are other checks detailed in each Pin Point Check Section other than what I am listing.

Service Code	Component
11	Electronic Controller (Clear memory Read codes … get 11 or 99 replace Electronic Controller)
12	Electronic Controller-Replacer ( Clear memory Read codes…get 12 replace Electronic Controller)
21	Main Valve (Disconnect main 2 Pin Plug on Hydraulic Actuator Assembly & measure resistance. 2 to 5.5 Ohms, service cable harness, any other reading replace Actuation Assembly)
22	LH Front Inlet Valve (Disconnect 7 pin connector on Valve Block, measure resistance Pin 7-6, 5-8 ohms service harness, other reading replace valve block).
23	LH Front Outlet Valve(Disconnect 7 pin connector on Valve Block, measure resistance Pin 7-5, 5-8 ohms service harness, other reading replace valve block).
24	RH Front Inlet Valve (Disconnect 7 pin connector on Valve Block, measure resistance Pin 7-1 5-8 ohms service harness, other reading replace valve block).
25	RH Front Outlet Valve (Disconnect 7 pin connector on Valve Block, measure resistance Pin 7-2, 5-8 ohms service harness, other reading replace valve block).
26	Rear Inlet Valve (Disconnect 7 pin connector on Valve Block, measure resistance Pin 7-3, 5-8 ohms service harness, other reading replace valve block).
27	Rear Outlet Valve & Ground (Requires use of EEC Break-out Box)
31	LH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
32	RH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
33	RH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
34	LH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
35	LH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
36	RH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
37	RH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)r
38	LH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
41	LH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
42	RH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
43	RH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
44	LH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
45	LH Front and one Other Sensor Signal (Requires EEC Break-out Box to check harness)
46	RH Front and one Other Sensor Signal (Requires EEC Break-out Box to check harness
47	Missing both rear sensor signals (Requires EEC Break-out Box to check harness
48	Missing three of four sensor signals (Requires EEC Break-out Box to check harness
51	LH Front Outlet Valve (Requires EEC Break-out Box to check harness)
52	RH Front Outlet Valve (Requires EEC Break-out Box to check harness
53	Rear Outlet Valve (Requires EEC Break-out Box to check harness)
54	Rear Outlet Valve (Requires EEC Break-out Box to check harness)
55	LH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
56	RH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
57	RH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
58	LH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
61	Fluid Level Indicator Circuit (FLI)and Pressure Warning Switch (PWS) Circuit (For FLI disconnect 5 pin connector on fluid reservoir measure pin 1 & 2 for resistance > 2 ohms replace indicator, For PWS disconnect Pressure Switch connector measure pins 3 & 5 should have a short if not replace Pressure Switch FOR PWS CHECK SYSTEM MUST BE PRESSURIZED)
71	LH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
72	RH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked for continuity to vehicle ground. If there is continuity…replace wheel sensor)
73	RH Rear Sensor ((Requires EEC Break-out Box to check harness but sensor can be checked for continuity to vehicle ground. If there is continuity…replace wheel sensor))
74	LH Rear Sensor (Requires EEC Break-out Box to check harness but sensor can be checked for continuity to vehicle ground. If there is continuity…replace wheel sensor)
75	LH Front Sensor Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
76	RH Front Sensor (Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
77	RH Rear Sensor Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
78	LH Rear Sensor Requires EEC Break-out Box to check harness but sensor can be checked 800 - 1400 Ohms is good. Other than that…replace wheel sensor)
88	Electronic Controller (Clear memory Read codes … get 11 or 99 replace Electronic Controller)
99	Electronic Controller (Clear memory Read codes … get 11 or 99 replace Electronic Controller)

If you come up with Wheel Sensor Codes make sure to check the indicator rings for missing teeth or other damage. It is also important to maintain proper gap between the sensor and the rings. Although this is not adjustable, faulty wheel bearings which allow the wheel to "float" axially too far can be a source of problems.

That is really the only things that can be done as a diy hope this helps as I have worked on many of these systems in the past. Good Luck