Hello everyone. Really appreciate all the info on here. Been learning a lot about my 1997 F350 Crew Cab 7.3L Truck. I have an intermittent ABS light. Brakes are working well. The previous owner stated that the ABS light began to flash after he tried cranking the truck with a bad battery. He replaced the battery and ABS light came on then went off.
I drove it for a couple of weeks and never saw it then it started to come on. Before checking the RABS code I changed the VSS on the rear diff and changed the diff fluid. Also I noticed the third brake light was melted so I replaced that. Fuses under the steering wheel are good. I also checked vacuum pressure at the brake booster and that 23mmhg which is good I believe. And my brakes feel great.
I finally checked the RABS code and got code 12. So now I am trying to figure out where my problems lies. I found the code 12:
12.1 CHECK WARNING LIGHTS Work fine
12.2 CHECK THE BRAKE FLUID LEVEL IN THE MASTER CYLINDER Full
12.3 VERIFY FLOAT BUOYANCY Float moves up and down freely
12.4 CHECK CIRCUIT 531 (DG/Y) FOR A SHORT TO GROUND What circuit is this?
12.5 CHECK THE DIODE/RESISTOR ELEMENT Where is this found?
12.6 CHECK CIRCUIT 512 (T/LG) FOR A SHORT TO GROUND ANd this one?
12.7 CHECK THE IGNITION SWITCH doubt this it but where is this one?i thi5nk this is the three wire one coming off the reservoir. How do I test this? Continuity? Voltage? I have a multimeter but I am very inexperienced with electrical testing[/COLOR]
12.9 CLEAR CODES/PULL CODES I tried clearing the code but it comes right back

If anyone could help I would really appreciate it. Thanks a lot

 

I wounder if the t /lg is a trailer light plug? I have a light on and forgot to check this one myself.

 

Looks like the DG/Y (dark green/yellow) wire is in the connector at the brake reservoir.

The T/LG (Tan/Light Green) one is there too.

Here is a PDF with some images to help.

Kevin

 

Thanks you! That should help.

 

Well the diode appears to be good (I am reading .573v across when checking continuity). When I push my float down in the brake fluid reservoir I do not get a red brake light on the instrument panel. Does that mean my fluid reservoir switch is bad?

I see the DG/Yellow wire and BK wire that go into the fluid reservoir. Should I have 12V in both DG and Yellow pins? And the black wire should be grounded (so check continuity between black wire and ground?). I don't see how I can test the switch other than pushing the float down. Sorry for my ignorance with electrical testing.

Appreciate any guidance.
Jake

 

I went out to check on my truck, I ohmed out the black wire in the 3 wire connector under the fluid reservoir and it was .23 ohms from the negative battery. Both the dark green/yellow and the tan/light green wires have battery voltage with the key on.

I also pushed my float down and my red brake warning light in the cluster didn't come on. I will have to do some more reading on this one. My ABS light is off too though and both pass key on bulb check.

You didn't replace the third brake light with a LED one did you?

Kevin

 

Thanks Kevin. I'll check for voltage on both wires.
I did. It replaced the third brake with LED but the brake bulb was burned out. Replaced with a new bulb and socket. It's working fine now. I thought that was gonna be my short for sure but apparently not.

I was just looking at the Hydraulic control valve and it is pretty dirty with oil and maybe even a little brake fluid. I gotta clean that off and check the connector somehow. I don't think that's on the 12 code checklist though.

 

The guys on here say that using a LED bulb can mess with the ABS system and the transmission shifting and torque converter lock up.

You might want to try a regular bulb in there to test and see if that helps.

Kevin

 

I am sorry. I should have read what I wrote. I am typing from my iPhone. I DID NOT USE AN LED in the third brake light. I used the same type bulb that was burned out.

 

This may help with the trouble shooting......

1996 Bronco/F-Series Workshop Manual

Go to section 06, then click on section 06-9A, then click on Symptoms Chart.

 

My tan wire definitely doesn't have any voltage. The green has 12v and almost nothing off the tan wire. Looks like this three wires come out of the distribution box. All my fuses are good. I just triple checked. What the heck does that mean?

 

I am not sure where the system diode is. In the service manual it says "under" the distribution box. I thought it was the diode (looks like a fuse) that's in the distribution box. But maybe that's not it. In the service manual it says the system diode keeps the code 12 from erroneously appearing when the brake is applied. Maybe I will try getting under the distro box. I will also check the stop lamp switch on the brake pedal but my brake lights are all functioning appropriately with no blown fuses so how could that be it?

 

Well as a last ditch attempt before disabling the RABS I replaced the master cylinder reservoir and low and behold my ABS light went off. Man. Should have done that first.

 

Sorry I didn't get back with you. But I am glad you did get your ABS light off.

I did more testing on mine that I will put here for anyone that finds this in the future.

When testing I get 12 volts on the DG/Y wire and the T/LG wire while still plugged in the fluid reservoir.

When I unplug the connector, the DG/Y wire still has 12 volts, and the T/LG has 0 volts.

I worked my float up and down a few more times and the red brake warning light would finally come on when I had the float held down.

Also, if I jump the Black wire with the Tan/Light Green wire (or probably the Green/Yellow), the brake warning light will come on, simulating the switch activating if the fluid was low.

Just some information for you guys.

Kevin