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  #1  
Old 08-15-2005, 02:53 PM
fordguy4life fordguy4life is offline
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ABS and brake light on

I have a '95 Aerostar where the two lights are always on. I'd like to pull the codes if i can. Does anyone if this year has the RABS or the RABS II module. Or is the diagnostic connector the same?
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  #2  
Old 08-15-2005, 08:12 PM
fordguy4life fordguy4life is offline
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Found the connector and got a code "12'" out of the module. Don't see any leakage and master was close to full. Filled the master but ABS and brake light still on. Is it possible the module needs to be reset? Tried disconnecting the battery cable for 30 mins. Lights still on. Any suggestions?
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  #3  
Old 08-15-2005, 09:07 PM
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96_4wdr 96_4wdr is offline
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will post diagram picture on my website

http://home.comcast.net/~classical_man/wsb/html/view.cgi-photo.html--SiteID-2372107.html

Description
Code 12 is generated when the anti-lock electronic control module detects that the brake fluid level in the brake master cylinder reservoir (2K478) is low for one or more seconds. It can also be generated by a short in the stoplight circuit.


Possible Contributing Base Brake Component/Vehicle Wiring Concerns

l Low brake master cylinder fill level

l Brake fluid leaks in vehicle brake system

l Worn or damaged master cylinder brake fluid level switch, or brake fluid level circuit shorted to ground

l Brake master cylinder reservoir float that sticks in the bottom of brake master cylinder reservoir or does not float

l Failed diode-resistor element in stoplight circuit

l Damaged ignition switch

l Ground short in Circuits 512 (T/LG) or 531 (DG/Y)

l Damaged anti-lock electronic control module

Note: Use Rotunda 73 Digital Multimeter 105-R0051 or equivalent for electrical tests.
BS use any high impdeance 1 megohn or more digi multimeter you got, just like a good woman, why change? Dance with what you brung

² 12.1: CHECK WARNING LIGHTS
² 12.2: CHECK BRAKE FLUID LEVEL IN MASTER CYLINDER
² 12.3: VERIFY FLOAT BUOYANCY
² 12.4: CHECK CIRCUIT 531 (DG/Y) FOR GROUND SHORT
² 12.5: CHECK DIODE/RESISTOR ELEMENT
² 12.6: CHECK CIRCUIT 512 (T/LG) FOR GROUND SHORT
² 12.7: CHECK IGNITION SWITCH
² 12.8: CHECK BRAKE FLUID LEVEL SWITCH
² 12.9: CLEAR CODE/PULL CODE


Pinpoint Test Code 12, Loss of Hydraulic Brake Fluid During an Anti-Lock Stop


12.1 CHECK WARNING LIGHTS


l Key OFF.

l Locate and disconnect the diagnostic connector from its mating half (Circuits 571 [BK/O] and 483 [R]).

l Reconnect diagnostic connector.

l Key ON.

l Do BOTH the red BRAKE and yellow RABS lamps come on?

Yes
HARD fault. GO to «12.2».

No
If the brakes have been serviced recently, or if brake fluid has been added to the system recently, MOST likely, the Code 12 was falsely set at that time and the RABS is OK. If this is NOT the case, GO to «Pinpoint Test ID» for intermittent diagnosis procedures for the affected circuits. REFER to the system schematic for this pinpoint test. If yellow RABS lamp is ON and Code 12 is present, SERVICE open circuit on Pin 2, Circuit 512 (T/LG).

12.2 check brake fluid level- obvious

12.3 VERIFY FLOAT BUOYANCY

l Remove the brake master cylinder filler cap.

l Attempt to push down the float with a clean, blunt steel implement, then let it float back up.

l Does the float go down then float back up?

Yes
GO to «12.4».

No
The float stays on the bottom of the brake master cylinder reservoir. REPLACE the brake master cylinder reservoir. BLEED the brake system. GO to «12.9».


12.4 CHECK CIRCUIT 531 (DG/Y) FOR GROUND SHORT


l Key OFF.

l Disconnect brake fluid level switch harness connector.

l Disengage parking brake.

l Check for ground short on Circuit 531 (DG/Y) at brake fluid level switch harness connector.

l Is there a ground short?

Yes
REPAIR ground short in Circuit 531 (DG/Y). RECONNECT all components. GO to «12.9».

No
GO to «12.5».

12.5 CHECK DIODE/RESISTOR ELEMENT


l Engage parking brake.

l Check for ground short on Circuit 531 (DG/Y) at brake fluid level switch harness connector.

l Is there a ground short?

Yes
REPLACE resistor/diode element. RECONNECT all components. GO to «12.9».

No
GO to «12.6».
12.6 CHECK CIRCUIT 512 (T/LG) FOR GROUND SHORT


l Key OFF.

l Disconnect battery ground cable.

l Disconnect fluid level switch.

l Disconnect ignition switch.

l Disconnect anti-lock electronic control module.

l Check for short to ground on Pin 2 of anti-lock electronic control module harness connector (Circuit 512 [T/LG]).

l Is there a ground short?

Yes
REPAIR ground short in Circuit 512 (T/LG). RECONNECT all components. GO to «12.9».

No
GO to «12.7».
12.7 CHECK IGNITION SWITCH

l Reconnect ignition switch.

l Check for short to ground on Pin 2 of anti-lock electronic control module harness connector (Circuit 512 [T/LG]).
l Is there a ground short?
Yes
REPLACE ignition switch. RECONNECT all components. GO to «12.9».
No
GO to «12.8».
12.8 CHECK BRAKE FLUID LEVEL SWITCH

l Reconnect brake fluid level switch.

l Check for short to ground on Pin 2 of anti-lock electronic control module harness connector (Circuit 512 [T/LG]).
l Is there a ground short?
Yes
REPLACE brake fluid level switch. RECONNECT all components. GO to «12.9».
No
REPLACE anti-lock electronic control module. GO to «12.9».
12.9 CLEAR CODE/PULL CODE

l Key OFF.
Note: When the battery ground cable has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 miles) or more to relearn the strategy.

l Verify all connectors are installed.

l Locate and disconnect the diagnostic connector from its mating half (Circuits 571 [BK/O] and 483 [R]).

l Key ON.

l Begin diagnostic trouble code flashout by grounding Circuit 571 (BK/O) for 1 second.
l Was DTC 16 or 12 retrieved?
Yes
DTC 16. CO to «Pinpoint Test DT4».
Yes
DTC 12. If all steps are complete, GO to «Pinpoint Test ID». If all steps are not complete, return to the last step completed and continue.
No
A different code. GO to pinpoint test for corresponding DTC.

Last edited by 96_4wdr; 08-15-2005 at 09:53 PM.
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  #4  
Old 08-16-2005, 07:48 AM
Baggins Baggins is offline
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I know this is going to sound really stupid but.......... check to see if both of your rear brakes lights are burned out.

I had exactly the same symptons one time, and that is what it turned out to be. The only thing I could deduce is that somehow with both the bulbs in a "failed" situation it somehow tripped a safety circuit.

Dan
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Old 08-16-2005, 10:09 AM
Muffinman Muffinman is offline
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You sure it's not code 13? If so look under the Ashtray and take the connector and wiggle it. Id that does not work the senser or wire connector on the Master Cylinder is bad or lose. Try pulling the Senser out "Black Tower Thing" below the Master cylinder and clean it with contact cleaner.
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  #6  
Old 08-16-2005, 10:30 AM
fordguy4life fordguy4life is offline
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Wow! Thanks for the help and the detail guys!
My wife left the drivers window open in just about a "monsoon". Everything else seems to work since it's dried. I think this might be a little more "fun" though....
B....
Unfortunately the brake lights are both working fine. My vehicle issues are never that simple.
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Old 08-16-2005, 10:32 AM
fordguy4life fordguy4life is offline
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11 short flashes and 1 long one...
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  #8  
Old 08-16-2005, 11:06 AM
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96_4wdr 96_4wdr is offline
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RABSII code 12
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  #9  
Old 08-16-2005, 11:14 AM
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<!--StartFragment --> http://www.asashop.org/autoinc/jan99/techtips.htm
Tech Tips



Ford rear anti-lock brakes

<CENTER>by Jamie MacFarland</CENTER>The Ford Aerostar has been equipped with rear anti-lock brakes (RABS) since 1990.

Though all of Ford's rear anti-lock systems are basically the same, one mild difference is the addition of a pressure differential switch (Delta P) found in the Aerostar's fluid level circuit. This Delta P switch is found in one of two places: On 1990-1991 Aerostars, the Delta P switch is found screwed into the front of the master cylinder. On 1992 and newer Aerostars, this switch is located on the combination valve assembly. In either location, the job of the Delta P switch is to alert the driver and RABS module in the event of a hydraulic problem.

The Delta P switch has given many technicians headaches, mostly due to the lack of proper documentation (or complete absence of documentation) in many service manuals. Typically, if there's a problem in the fluid level circuit, customers will complain that the anti-lock warning light is on or both the red brake warning light and the anti-lock warning light are on.

The bottom line on this circuit: The RABS module needs to see battery voltage at pin No. 2. And if it does not, the anti-lock system assumes that there's a problem and illuminates the anti-lock warning lamp. The problem that slows down many technicians during diagnostics when this happens is the absence of a trouble code for this fault (on pre-1992 RABs 1 vehicles). This lack of a trouble code, coupled with the often poorly documented testing procedures, has led to the unnecessary replacement of many anti-lock modules. Beginning in 1992, the RABS 2 system began incorporating a code 12 - the result of low voltage to pin No. 2 of the RABS module.

Note: It is possible to get a code 12 on a pre-1992 Aerostar if the anti-lock module has been replaced because a RABS 2 module is what you'll get if you go to the parts department for a module replacement. The RABS 2 module is compatible for older models and so is used as a replacement for the earlier RABS 1 modules.

The two most common problems you'll encounter in the fluid level circuit of an Aerostar is 1) a poor connection at the fluid level switch located under the master cylinder reservoir (resulting in only the anti-lock warning lamp being illuminated) or 2) the Delta P switch is grounding out the circuit (resulting in both the red brake warning lamp and the anti-lock warning lamp). This Delta P switch is designed to ground the circuit when there's a pressure difference between the primary and secondary hydraulic circuits (broken brake line, etc.). Often the Delta P switch will ground out the fluid level circuit - when in reality there is no hydraulic problem at all. To see if the Delta P switch is the cause of the illuminated warning lamp(s), disconnect the two-wire connector (on the Delta P switch) and jump the two wires together. If the light sequence returns to normal, the Delta P switch is the cause.

To save time: Before you even try to pull a code, verify that the red brake warning lamp illuminates when the ignition switch is turned to the crank position. This is a bulb check function incorporated in the red brake warning lamp circuit. If you don't see the red brake warning lamp when you crank the engine over ... find out why not! Chances are good that the lack of illumination during the bulb check routine is the result of a poor connection at the fluid level circuit. And remember, on pre-1992 Aerostars, there is no trouble code for this condition!

Jamie MacFarland is ASE master and L1 certified. He is an IDENTIFIX repair hotline Ford specialist with 13 years of experience.
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  #10  
Old 08-16-2005, 11:21 AM
DOUG5G DOUG5G is offline
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Have you tried removing the connector from the proportioning valve just below the master Cylinder. If the ABS light goes out then the switch needs to be replaced. I had the same symptoms and it was just a $20 switch that got corroded. The valve is silver approx 1x3x6 incles long. My switch was black plastic and had a connector that was easy to remove. The brake should always come on once the ABS light comes on. Troubleshoot around the ABS light first.

Doug
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Old 08-16-2005, 12:14 PM
DOUG5G DOUG5G is offline
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WOW. 96_4WD and I must have responded at the same time. He is describing the same thing except his is in much better detail. What it comes down to is removing the connector off the proprtioning valve (Delta P) and seeing if anything changes. Then shorting it out to see if it goes back to an unfaulted condition.

Good Luck
Doug
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Old 08-16-2005, 02:35 PM
cagedriver cagedriver is offline
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i have been having a problem with my brakes as well. when i apply pressure at the pedal, it feels as though the abs switch is kicking off and on, and it feels like the brakes are doing the same. once stopped, i can hear a clicking sound and "feel" the sound/switch in the pedal. it does this with only occasionally lighting the abs light. any ideas?
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Old 08-17-2005, 09:11 AM
fordguy4life fordguy4life is offline
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Looks like it's the Delta P switch. When I short the connector the lights go off. I'll stop and get a new one tonight. Thanks for the help guys!!!
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Old 08-17-2005, 08:51 PM
DOUG5G DOUG5G is offline
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After you remove the switch, look in the holde and please tell me if you see green gunk inside
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Old 08-18-2005, 10:22 AM
Bear River Bear River is offline
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Bear River has a very good reputation on FTE.Bear River has a very good reputation on FTE.Bear River has a very good reputation on FTE.Bear River has a very good reputation on FTE.
Also, this may sound dumb, but make sure the connector to the fluid level switch is plugged in. On our van, it wasn't.
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Old 08-18-2005, 10:22 AM
 
 
 
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