I have a 1996 Explorer with a V8 and 4 wheel disk that has an ABS light that stays on all the time (with Key on only or if the engine is running and vehicle moving).
Using a scan tool, I was able to pull ABS Code C1194 (ABS outlet valve coil LF Circuit Failure). From the research that I did, it seemed to point to the ABS Module. I replaced the module (located in the left fender next to the battery) and the light is still on.
I have also checked the continuity of all the sensors.
When I had a problem with my 98 Mountaineer, it kept telling me there was a problem with the left side also. I changed the wheel bearing and sensor, drove it a couple miles, and checked to see if the code cleared. It didn't. My light would only come on once and a while. But after I changed that, the light never came back on. I checked for a code a couple weeks later and it was finally gone. My ABS was working fine the hole time. Get on a slippery surface and slam on the brakes to see if your ABS is working. You don't need to be going very fast. I did it on a gravel road going about 20mph.
My ABS light would only come on once and a while, then it would shut off if I shut the Merc off and re-start it. But the code would still be there, no light, just the code. With the ABS systems you don't have the option to clear the code like you do with the OBDII part of it. ABS codes will clear by them selfs once the problem is gone. I even unhooked my battery, then once I hooked it back up I check to see if the code was gone, and it was still there. I didn't even drive it yet and the code was still there. But after driving it a few weeks, I figured I would check it again and it was gone. But the hole time, my ABS still worked the way it was suppose to, even when the code was still there.
Now I have done other work for other peoples cars with ABS problems. As soon as I fixed it, the code was gone before I left my driveway.
My light is on all of the time. I also found the code stays stored all the time even after unhooking the battery. But to read the codes, I have to turn the key on for the code reader. I believe this triggers the ABS code since the ABS starts its self checking once the key is on.
If the light is on all the time, then there is an open in the circuit somewhere. Since I have replaced the ABS module, then I have removed one element but wanted to know if there is another circuit perhaps in the pump that could be causing the problem.
Hmmm..... I don't know what to tell you. Check all your connections. It seems like there are solenoid's on the ABS pump its self. Check the plug where it plugs in from the wheel sensor to the main wire. They are a two prong type plug and sometimes they get bent when you plug them in.
I found a wiring diagram for the ABS system. I will check all the pin outs for all sensors (this will eliminate any broken wires or bad connections up to the Module). Plus, it shows the Left Dump valve in the Hydraulic unit. It doesn't give a resistance for the dump valve but there is a right dump valve that should have a relative resistance to the Left one. I believe it must be solenoid type so I'm hoping to find an open on the left dump valve.
If anyone one knows what the resistance should be for the dump valves of the Hydraulic unit or know how to test it, any advice would be greatly appreciated.
I did a resistance check on all the pins at the ABS Module and found all sensors to be within spec. I did find the resistance of the left dump valve to be 6 meg ohms (showing an open) while all the other valves of the ABS pump to be around 10 ohms. So I am going to ebay to find a used ABS pump.
I bought an ABS pump off ebay and that fixed the problem. I plugged in the two connectors of the new pump (before hooking up the hydraulic lines) and the light went out. I wanted to make sure this fixed the problem before swapping pumps.
To check the new pump, one connector has two wires and go to the pump motor. The resistance is around 0.5 ohms (can be checked by placing the ohm meter across each wire connector). The second connector has 8 wires. All the wires are the same color so you have to look at the harness that plugs into the plug to find the Orange with Yellow stripe (there are two wires like this and either one can be used, that leaves 6 other wires to be checked). Now place one ohm meter lead where the Org/yel wire would make contact and measure each other wire that has the same color. You should see about 5 -10 ohms for the six valves inside the ABS pump. I had one of my valves show an open.
If the ABS pump shows good, then it will be either the harness from the ABS pump to the ABS module or the ABS Module is bad.
Hope this helps other with troubleshooting this problem.
The ebayer is 'autopartswiz'. since all the ABS pumps are used, make sure you buy one with a warranty. Most will give a 7 day to 14 day return. They say the pumps have been tested but there is no way to verify that.
Did you have a chance to resistance check your pump to verify if it is good?