Question about 1988 Lincoln Mark VII

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Check antilock brake light is on. I cleaned all four sensors and discs.Whats next the accumulator?

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  • RayBigs Apr 17, 2009

    ...had the same year same problem..added brake fluid to the resevoir and light went off. My '88 now goes thru way too much brake fluid. I have to fill resovoir every day now.

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  • 47 Answers

You have to go to a shop and ask them to check it.
The mechanic will plug on a portable instrument and take the car for a test drive.
The wheel sensor that is not working will not show up.
I had this problem and that is what they did.

Posted on Mar 10, 2009

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Brake warning lights


Many repair shops can read the ABS codes also - especially shops that specialize in tires and brakes.

The codes will likely identify if a specific wheel sensor is mis-behaving / failing, or a worst-case situation: the ABS Control Module is failing (expensive).

The sensors, located behind each wheel, can be checked for accumulated road 'gunk' and cleaned. Also look for any frayed/broken sensor wires.

NOTE: The sensor sit about .25" away from a gear-type ring on the backside of the wheel - the 'exciter ring'. It's the teeth passing in front of the sensor that creates the signal sent to the ABS control module.
NOTE: The ABS Control Module reads the speed of each wheel and 'pulses' the level of braking to each wheel according to if it thinks it is skidding on ice/wet surfaces.
Problem with the Anti-Lock Brake System. Take it to a professional and I believe it means the Antilock Brake System is disengaged. Means a code has been stored in the abs computer. Standard obd tester cannot check these codes. Take to dealer service shop.

Jun 04, 2013 | 1998 Ford Expedition

1 Answer

I have 1999 range rover ABS lights is on all the time.


this is a fairly common problem, the most obvious cause is the electrical connection to one or more of the antilock brake sensors on the brake discs ( have you been off road?), if not you have probably had a Antilock sensor failure.

Apr 01, 2013 | 1999 Land Rover Range Rover

1 Answer

Oxigen sensor


OK, so now I know that you have a 1999 Isuzu Trooper Equipped with a 3.5L V6 DFI DOHC engine, 4-wheel drive, four wheel disc brakes, four wheel antilock system, 108.70 in. wheel base, with a standard curb weight of 4465 lbs.

WHAT ABOUT "oxygen sensor"???

Apr 14, 2012 | 1999 Isuzu Trooper

2 Answers

ABS and OD lights are on and transmission is kicking out could this all be related


Could be a fuse or a wheel speed sensor; next, check the tone rings on the axle shafts and see if they are not broken.

I quote this information from Jeep lover's...

The amber ABS warning lamp is located in the instrument cluster. It is used to inform the driver that the antilock function has been turned off due to a system malfunction. The warning lamp is controlled by the CAB and/or the main relay through an in-harness diode. The CAB controls the lamp by directly grounding the circuit. The main relay grounds the lamp circuit when it is de-energized.
The re BRAKE warning lamp is located in the instrument cluster. It can be activated by application of the parking brake or leak in the front or rear wheel brake hydraulic circuit.
The antilock brake controller (CAB) is a microprocessor-base device that monitors wheel speeds and controls the anttlock function.
The primary functions of the CAB are:
- monitor wheel speeds
- detect wheel locking tendencies
- control fluid pressure modulation to the brakes during antilock stop operation
- monitor the system for proper operation
- provide communication to the DRB while in diagnostic mode
- store diagnostic information in non-volatile memory
The CAB continuously monitors the speed of each wheel. When a wheel locking tendency is detected, the CAB will command the appropriate valve to modulate brake fluid pressure in its hydraulic unit. Brake pedal position is maintained during an antilock stop by being a closed system with the use of 3 accumulators. The CAB continues to control pressure in individual hydraulic circuits until a wheel locking tendency is no longer present. The CAB turns on the pump/motor during an antilock stop.
The antilock brake system is constantly monitored by the CAB for proper operation. If the CAB detects a system malfunction, it can disable the antilock system and turn on the antilock warning lamp. If the antilock function is disabled, the system will revert to standard base brake system operation.
The CAB inputs include the following:
- four wheel speed sensors
- stop lamp switch
- ignition switch
- main relay voltage
- pump/motor relay output
- diagnostic communication ISO/K
- G switch (acceleration switch)
The ABS main relay is located in the power distribution center (PDC). The main relay has two functions. First, when the relay is energized, it supplies power to the valve/solenoids in the valve block assembly and the pump/motor relay coil. Second, when the relay is de-energized, it supplies a ground to turn on the ABS warning lamp. The main relay is controlled by the CAB. The CAB energizes the main relay when it receives an ignition input signal.
The ABS pump/motor relay supplies power to the pump/motor. It is also located in the PDC. The relay coil is powered by the main relay and the coil ground is controlled by the CAB. The pump/motor relay is a special five-terminal relay and should not be replaced with a standard relay.
One wheel speed sensor (WSS) is located at each wheel and sends a small AC signal to the control module (CAB). This voltage is generated by magnetic induction when a toothed sensor ring (tone wheel) passes by a stationary magnetic sensor (wheel speed sensor). The CAB converts the AC signals into digital signals for each wheel.
The front wheel speed sensor air gap is NOT adjustable. The correct front wheel speed sensor air gap is from 0.40mm to 1.3mm. Preferred rear sensor air gap for drum brake systems is 1.1mm. Acceptable air gap range is 0.92mm to 1.275mm. For rear disc brake systems, the preferred rear sensor air gap is 1.2mm. Acceptable air gap range is 0.95mm to 1.45mm. All wheel speed sensors have a resistance between 900 and 1300 ohms.
Correct antilock system operation is dependent on tone wheel speed signals from the wheel speed sensors. The vehicle's wheels and tires should all be inflated to the recommended pressures for optimum system operation. Variations in wheel and tire size or significant variations in inflation pressure can produce inaccurate wheel speed signals; however, the system will continue to function when using the mini-spare. When driven over rough road surfaces, the rear wheel speed sensor signals may be erratic and cause a false trouble code (drum brakes only).
Diagnostic trouble codes are retained in memory until erased using the DRB, or automatically erased after 50 key cycles.
Ensure you are using a DRBIII scan tool properly connected to the data link connector located under the dash to the right of the steering column.
Select "Anti-lock Brakes" the "Teves ABS". Turn the ignition on.
Read and record all ABS diagnostic trouble codes. If the "Valve Power Feed Circuit" trouble code is present, it must be repaired before prior to addressing any other DTCs.
If there are no trouble codes present, select "Inputs/Outputs" and read the brake switch input as you press and release the brake pedal. If the display does not match the state of the pedal, check for 8 volts at the brake lamp switch output circuit. If the voltage is not present, repair the open brake lamp switch output circuit. If the voltage is present, replace the CAB.
If the display does match the state of the pedal, read the "G-Switch" status, with the vehicle on a level surface, both switches should read "CLOSED". If the status is not correct, make sure the G-Switch is properly mounted and connected (under the driver's side rear seat). If it looks correct, you'll have to check for voltage to the G-Switch.

Hope helps.

Jan 18, 2011 | 1995 Jeep Grand Cherokee

1 Answer

2005 jeep grand cheroke limited with A hemi, been to the dealer more times then I can count, and still to this day the same problem. The service elect brake system light illuminates intermit and so for...


The braking force of the rear wheels is controlled by electronic brake distribution (EBD). The EBD functions like a rear proportioning valve. The EBD system uses the ABS system to control the slip of the rear wheels in partial braking range. The braking force of the rear wheels is controlled electronically by using the inlet and outlet valves located in the HCU. The HCU is a Hydraulic control unit. The HCU consists of a valve body, pump motor, and wire harness.

Did they check for DTC (diagnostic trouble codes) in the system? if so, what were they?

Accumulators in the valve body store extra fluid released to the system for ABS mode operation. The pump is used to clear the accumulator of brake fluid and is operated by a DC type motor. The motor is controlled by the ABM.
The valves modulate brake pressure during antilock braking and are controlled by the ABM.
The HCU provides four channel pressure control individually to all the front and rear brakes. Each of the four channels control the rear & front wheel brakes individually.
During antilock braking, the solenoid valves are opened and closed as needed. The valves are not static. They are cycled rapidly and continuously to modulate pressure and control wheel slip and deceleration.
During normal braking, the HCU solenoid valves and pump are not activated. The master cylinder and power booster operate the same as a vehicle without an ABS brake system.
During antilock braking, solenoid valve pressure modulation occurs in three stages, pressure increase, pressure hold, and pressure decrease. The valves are all contained in the valve body portion of the HCU.


PRESSURE DECREASE The outlet valve is opened and the inlet valve is closed during the pressure decrease cycle.
A pressure decrease cycle is initiated when speed sensor signals indicate high wheel slip at one or more wheels. At this point, the ABM closes the inlet then opens the outlet valve, which also opens the return circuit to the accumulators. Fluid pressure is allowed to bleed off (decrease) as needed to prevent wheel lock.
Once the period of high wheel slip has ended, the ABM closes the outlet valve and begins a pressure increase or hold cycle as needed.


PRESSURE HOLD Both solenoid valves are closed in the pressure hold cycle. Fluid apply pressure in the control channel is maintained at a constant rate. The ABM maintains the hold cycle until sensor inputs indicate a pressure change is necessary.


PRESSURE INCREASE The inlet valve is open and the outlet valve is closed during the pressure increase cycle. The pressure increase cycle is used to counteract unequal wheel speeds. This cycle controls re-application of fluid apply pressure due to changing road surfaces or wheel speed.

Nov 09, 2010 | 2005 Jeep Grand Cherokee

1 Answer

95 isuzu rodeo anti lock brake lite staying on and brake paddle moving up and down


You probably have a bad wheel speed sensor, Most likely the sensor is telling your antilock system to activate, causing your brake pedal to pulse under your foot, you may have to take it and get it diagnosed. or check the wiring harness's, make sure they are properly connected, behind the front brake caliper if your vehicle is equiped with 4 wheel antilock, and the rear antilock may be either behind your brake drum or caliper, depending on disc or drum brakes on the rear. Some Vehichles have a single speed sensor located usually near the center of your rear axle,instead of individual sensors on the rear. look for a wiring harness connecting to the rear axle. It will likely be the only wiring connected into your rear axle. Hope this helps

Feb 14, 2010 | 1995 Isuzu Rodeo

1 Answer

The abs and trac lights stay on when the engine is running. how do I fix the problem ?


Something as simple as a different tire size can cause the abs to go nuts. I even had it where the two tires were the same size. But a different brand name. Each manufacture has their own tire sizing so not all tires a equal in size. Even though it says on the side of the tire that they are the same size.

Sometimes the cooper inside the insulation of the wires going to the sensors corrodes. Especially on the front units. It reads more ohms than normal but not open and is very intermittent. However moving the wires my make it work for a while. That's why replacing bearings seems to fix the problem but it comes back after a while.

You can test the speed sensors yourself...
Front sensor specs:
956 to 1240 ohms in 41 to 110 degree weather
at least 100mV AC (NOT DC!) volts when hub is spun by hand
Rear sensor specs:
950 to 1300 ohms in 41 to 110 degree weather
At least 100mV AC (NOT DC!) volts when hub is spun by hand

Here is some information from service bulletins that could be related to the problem. The traction control, antilock brakes, and tire inflation monitor all use wheel speed sensor input.

This first bulletin seems like it could be the problem because engine movement is involved:

GM Corporate Bulletin 00-06-04-049B
This Bulletin covers a problem that can cause multiple failures, one of which is an Antilock brake problem, and covers 2000-2003 Impala and Monte Carlo built prior to 2/03.
Check to make sure the wiring harness adjacent to the AC accumulator/dryer is not rubbing against the ac accumulator chaffing through the insulation of the wires in the harness.

GM Corporate Bulletin 03-05-25-008 overview:
GM front wheel speed sensor harness replacement - 2001-2003 Buick Century, Regal; 2001-2003 Chevrolet Impala, Monte Carlo; 2001-2002 Oldsmobile Intrigue; 2001-2004 Pontiac Grand Prix
This bulletin is about inspecting the harness going to the front wheel speed sensor for wear from contact with front suspension parts.
Repair harnesses/leads are available that can be spiced onto the main harness.
2001-2003 impala & Monte Carlo – Right side - 10340313
2001-2003 impala & Monte Carlo – Left side - 10340314

SERVICE BRAKES, HYDRAULIC:ANTILOCK:ABS WARNING LIGHT
• TSB #030525008 -- INTERMITTENT/CONSTANT ANTI-LOCK BRAKING SYSTEM (ABS) MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATED. *TT (NHTSA ID #10004719, OCTOBER 01 2003)

Hope helped.

Nov 05, 2009 | 2001 Chrysler Concorde

1 Answer

ABS light stays on


that has four wheel anti lock so your gonna need to either take all them off and clean ends it may correct the problem but more than likely your gonna have to take to a large shop that has abs computer to find which sensor is bad then correct the problem

May 23, 2009 | 2001 Nissan Maxima

1 Answer

Antilock brake light stays on


Start with checking the sensors on each wheel.  These will be the electrical wires that come from behind each wheel.  Also check that the tire pressure in each tire is the same.  Next, check your brake fluid level.
Sorry...that's all I can help you with.  Maybe someone else can help you from here.

Apr 21, 2009 | 1994 Buick Century

1 Answer

Anti lock brakes


make sure the slides on the calipers (they acuate the pads) are cleaned and the slides are lubed with a high temp brake caliper grease . the other possibility is a faulty master/brake booster

Jul 20, 2008 | 1985 Audi 5000 S

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