Well, I got my info center.
Plugged it in and first fault is an S2B 04. Which translates as "2B Sensor/wiring open or short circuit." The manual lists possible causes as:
Sensor failures, sensor wiring open or short circuit. Sensor resistance should be 980 to 2350 ohms. Verify wire ties on sensor cables connected to air hoses are not too tight. Excessive grease may prevent secure sensor connections.
Other stored faults were
ECU 99 = "Internal ECU fault" Most likely the dead diode inside the ECU, which I replaced.
B+HI 92 = "Supply voltage at the ECU greater than 33V" .What most likely killed the ECU voltage protection diode. My truck had a dead alternator with a burned up voltage regulator when I got it
ISO 91 = "Faulty supply or 15amp fuse blown (Incorrect power sequence)" This one is self-explanatory.
SLW 43 = "Slow recovery, yellow channel" The possible causes listed in the manual are "Slow brake release, foundation brake mechanical faults, dry bearings, broken spring, restricted piping. Modulator fault. Check for kinks and blockages, etc. Incorrect piping or sensor wiring crossed. Inspect exciter ring for damage. Failed primary reservoir."
SLW 42 see above
After clearing the stored faults, the only one that shows up is S2B 04.
So the good news, I think, is that replacing the voltage protection diode "fixed" the ECU. The bad news, is that there are faults in the system unrelated to that. And I have no idea what the wheel sensors even look like or what the wiring is supposed to look like or where they may be found. But at least I know what terms to use in researching the problem, thanks to the scan tool.
All in all, I think it's a good idea to have access to one of these scanner tools if you run into problems with your ABS. Yes, you may have faults completely related to the ECU. Then again, you may have other faults.
Where do I stick the pointy metal probes?
