Originally Posted by 01SILVERGT
Yes, complete the circuit on the relay with 12volts. The same way you did it with the compressor when you tested it.
Thanks. Another person here sent me a couple of scanned pages from the Helm Vac & Electrical manuals which show a diagram of the LLS circuit. I think I understand it.
It appears that the solid state relay has 4 connectors - A B C D.
A is labeled as being connected to the power distribution box, always hot, on fuse #15, a 50 amp fuse. I can disconnect the relay and see if I have 12vdc on terminal A. If I do not, perhaps there is a problem w/ the wiring back to the distribution box or the fuse, where honestly I didn't think to look before). I can check continuity if I don't have 12vdc and see if there is a break in the wiring.
B is labeled as being 12vdc from the relay to the air compressor. Here, I can test continuity of the wiring from the relay to the compressor to make sure I don't have a wiring problem. Since B is switched by the relay it normally wouldn't be on unless their LLS computer says to switch it on.
C is labelled as a ground. I can test continuity here to ground on the chassis. If I have a bad ground, naturally the pump wouldn't turn on. Oddly enough, the diagram shows that the ground wire from the air compressor itself splices into this same line before it goes to ground, so I can eliminate two potential wiring problems at the same time.
Finally, D is labelled as 12vdc connected to the Air Suspension Module. I assume D is not normally energized unless the computer wants to pump up the system. So, this connector will normally be 0vdc unless the air suspension pump is being turned on. This line terminals at the 4WAS module, pin 18, so again with a little ingenuity I should be able to test continuity to make sure the wiring is secure.
If the wiring is secure, and I don't get 12vdc output on pin D when the LLS should engage the pump, I think its safe to conclude that the 4WAS module is toast, yes?
Does all this sound reasonable? I'm going to take a 1/2 day out of work tommorrow to try and fix it while there is still daylight.
Thanks for the tips on web sites too if I need to order another module. Is there a part # I should reference? The documentation another member sent to me doesn't show a part # for the 4WAS module.