Re: 1999 Merc Promax 200XL EFI -no spark on 1 side for all 3 cylinders
With NO RETURN on electrical parts you want to be SURE of any diagnosis before ordering any expensive NONE RETURNABLE parts.
Some motors kill spark on one bank for shifting, so you need to follow the troubleshooting directions of the CDI Guide or the factory service manual.
Once you find the fault, double check your work, retest again to positively PROVE the fault.
With all that out of the way, disconnect all Bias wires from both switchboxes and retest for spark on ALL cyls. If you now have spark everywhere then you have a bad Bias circuit on the box that was always sparking, causing the other box to hold-fire. If this proves to be then the factory recommends replacing the boxes as a pair. Side note; mark the Bad Bias box, both boxes will work perfectly fine on any of the 3 cyl motors as they do not use the Bias circuit.
I removed the white/black bias lead from the switchbox, but still not spark on all 3 cylinders, same side.
I also check the ohm reading from the terminal for white/black with lead removed and to ground and got 14000 ohms set on the 1K scale. (14x1000=14000) I got the same reading for both packs, but the manual says they should be 1300-1500 ohms...
Is this pointing to the problem with the switch boxes or a misprint on the numbers....?
I took ohm readings for the stator leads and they all fell within range.
Between BLUE and RED Stator Leads - 3500-4200 ohms at - R x 1000
Between BLUE/WHITE and RED/WHITE Stator Leads- 3500-4200 ohms at- R x 1000
Between RED Stator Lead and BLACK Stator Lead - 90-140 ohms at- R x 1
Between RED/WHITE Stator Lead and BLACK Stator Lead - 90-140 ohms at - R x 1
any thoughts welcome...
thx
