my abs light came on...pulled the abs code from the test connector...code 12...went thru the steps for diagnostic as per the haynes manual. i get to the step where you disconnect the master cylinder level switch. check for ground short on wire 531 dg/y. i get something like 10 ohms on my meter. is there supposed to be any reistance on this wire? i dont know if this is a 'partial' ground? the next step is to check the resistor/diode....the diode itself checks out ok, the resistor is also in the neighborhood of 10 ohms. apply the parking break, still 10 ohms on wire 531 dg/y.

i pulled the connector off the abs module to see if that was introducing anything to the system....still 10 ohms at 531 dg/y. i dont know if there is allowable 'resistance' for this wire, is 10 ohms considered a ground short? (actually, i forgot what range i was using on my meter, but i do remember it was '10'....whether it was 10, 10k etc i forget).

the only thing i didnt check was wire 512, t/lg from pin 2 on the the module to the master cylinder switch. i was curious as to what is considered a ground short before i went too far.

the master cylinder switch is working.

any advice would be appreciated.

thanks

 

Hi defed and welcome to FTE

I assume your master cylinder is full of fluid? The float isnt stuck down?
Ten ohms between the wire and ground would be a short to ground.
I think I'd probably start from scratch at the beginning of the pinpoint tests again and make sure you follow them very closely. They aren't always real clear what they want you to do.

 

thanks for the quick reply. you are right, the manual isnt that clear, and i made the mistake of getting the CD version rather than the book....never again!

yes the master cylinder is full and the float is up, and the flaot switch works, i checked by pushing it down and seeing if the 'connection' was completed.

i did go thru the darn pinpoints a couple times already. everything seemed to go fine up until the wire 531 checks (connects to master cylinder level sensor).

when checking for a ground short, a 0 ohm reading would be a complete short, correct? since it is like touching the 2 probes together.....you dont want continuity when touching the wire to the ground. or am i thinking backwards?

the one thing that is driving me nuts, because i cant remember now, if i was getting a 10 ohm reading, or a 10 k/ohm reading. i will have to check again tomorrow.

 

ok, i rechecked my ohm reading on wire 531 dg/y.....1st, i checked the resistance on the resistor in the power distribution box.....10 K/ohm...anyone know what that resistor should be? i can't read what it says on the side.

with the resistor in, i get a 10 K/ohm reading on wire 531 dg/y (NOT 10 ohms).

if i pull the resistor, i get Open Load, or a very high ohms, like 14 m/ohms.

thanks for any advice, i'm not the best when it comes to electrical stuff.

 

PINPOINT TEST P: DIAGNOSTIC TROUBLE CODE (DTC) 12 — LOSS OF HYDRAULIC BRAKE FLUID


P3 CHECK FOR SHORT TO GROUND CIRCUIT 531 (DG/YE)


1 Brake Fluid Level Switch C137

2

Measure the resistance between brake fluid level switch C137 Pin 3, Circuit 531 (DG/YE), harness side and ground.

l Is the resistance less than 5 ohms?

è Yes

REPAIR Circuit 531 (DG/YE). REPEAT System Pre-Check.

è No

Go to «P4».


P4 CHECK DIODE/RESISTOR ELEMENTS


1 Engage the parking brake.

2

Measure the resistance between brake fluid level switch C137 Pin 3, Circuit 531 (DG/YE), harness side and ground.

l Is the resistance less than 5 ohms?

è Yes

INSTALL a new resistor/diode element(s). REPEAT System Pre-Check.

è No

Go to «P5».


P5 CHECK FOR SHORT TO GROUND CIRCUIT 512 (TN/LG)


1 Ignition Switch C213

2

Measure the resistance between brake fluid level switch C137 Pin 2, Circuit 512 (TN/LG), harness side and ground.

l Is the resistance less than 5 ohms?

è Yes

REPAIR Circuit 512 (TN/LG). REPEAT System Pre-Check.

è No

RECONNECT the ignition switch C213. Go to «P6».


P6 CHECK IGNITION SWITCH


1 Anti-Lock Brake Control Module C238

2

Measure the resistance between anti-lock brake control module C238 Pin 2, Circuit 512 (TN/LG), harness side and ground.

l Is the resistance less than 5 ohms?

è Yes

INSTALL a new ignition switch; REFER to «Section 211-05». REPEAT System Pre-Check.

è No

RECONNECT the brake fluid level switch C137. Go to «P7».


P7 CHECK BRAKE FLUID LEVEL SWITCH


1

Measure the resistance between anti-lock brake control module C238 Pin 2, Circuit 512 (TN/LG), harness side and ground.

l Is the resistance less than 5 ohms?

è Yes

INSTALL a new brake fluid level switch. REPEAT System Pre-Check.

è No

INSTALL a new anti-lock brake control module; REFER to «Module—Anti-Lock Electronic». REPEAT System Pre-Check.

 

thanks for that....i am either blind because i did not see anything in my haynes about 5 ohms.

if that is the case, that should help me immensely. i was to the point of following the manual and then some. for example, to check 531, i unhooked it completely from everything, and had no ground short. so the wire itself is not grounded. i then did the same for the next wire, and so on. using that method, i would only get an ohm reading when 531 was hooked to the instrument panel. when completely isolated, it is not shorted.

bad news about the 5 ohm is that it might be the module....i will go thru it again w/ the 5 ohm limit. the 10k ohm measurement i was getting all the time was really throwing me off since my manual says nothing about what is tolerable. i think i check all the isolated wires for ground, and there is none, so that almost surely leads to a bad component...

i thank you for that info and will let you know what happens.

 

at wire 531 dg/y - 10k ohms
at wire 531 dg/y - parking brake on - 10k ohms
at wire 512 t/lg - ignition, battery, module disconnected - 1m+ ohms
at wire 512 t/lg - ignition reconnected - 600k-1m ohms
at wire 512 t/lg - fluid level reconnected - 600k-1m ohms

looks like a replacement of the module.

 

Let us know how things turn out.

 

anyone have a good source for inexpensive parts? i think autozone told me $180 for the module. i just dont want to spend that much and find out that it is NOT the module.


thanks.

 

How about a junkyard.

 

thought about that, but there isn't many large ones around here. do you happen to know what other years used the same module?


my original part # is F57F-2C018 AA....on one site i saw some w/ OE # F59F-2C018 AA and other variations (all w/ 2C018, but different prefix and different letters at the end)...none that matched mine exactly....how do you know what will fit what? or is 2C018 the most important part, as long as it is for rear wheel abs?

thanks for the advice.

 

Sorry, I can't help with that, maybe a parts store or a Ford dealer can tell you.

 

been a long time since i started this thread, and i finally got around to trying to fix my failed ABS. after going thru the diagnostics, everything checked good, so the final step is that the ABS module is bad.

so i finally get a module and put it in...and guess what? still the same trouble code. i tried to clear the memory as per the service manual, still showing a trouble code.

so, either there is another problem (not the module - and apparently nothing relating to code 12 since i checked all those areas), i didn't get the code cleared, or there is another problem that keeps killing modules.

anyone have any ideas? so much for technology!

thanks

Dave

 

i'm having a problem with the term 'ground short'...when i check a wire for a short, i am getting the same value as the resistor that the wire is connected to. for example, i measure the resistor alone at 10k ohms...when i check the wire that connects to it to ground, i also get 10k ohms...how can i get this unless the wire is grounded?

if i remove the resitor from the wire, i get 2,000k ohms to ground, which to me, isn't a ground short...

ideally, this wire would be grounded (tho it sohuldn't be), then i THINK it would solve my stupid abs problem.

 

I agree that the wire would be grounded.

Maybe the resistir is causing the short to ground but I still would expect more resistance.