4 PTT relays have gone bad on down side.

[GBCat2017]

Hi folks, new here but I need some advise, input. Just bought a used Cat with twin DF90 ‘s (2002) on it. It had been sitting for 4 years without starting. Only about 400 hrs on them. Once I sorted the fuse block, the port fired right up. After replacing EFI pump the starboard fired up. During the repair process, I noticed the relieve valve on the starboard PTT had one side broken off of the screwdriver slot. Installed a new one. But the PTT pump would not spin on the lowering (down) mode. Tested relay (an after-market, non-Suzuki part), found to be bad, replaced. PTT motor would spin during up but not down. Traced down a bad cowling mounted switch. Replaced. PTT motor now spun both up and down as it is supposed to do. Started the bleeding process. Lots of foam, but no movement. Down relay clicking but no PTT motor reaction. Tested relay, found to be bad. Ordered new part, but then it hit me- this will be the 4th relay to be installed on this engine. Question: what causes the down PTT relay to “short out” or “burn up”?

[redlowrey]

How are you testing the relay, you do realize when you press the down button the ptt motor will go to ground on the up relay ground, have a look where the ground from the up relay and the down relay are spliced and ground on the block. That is probably where your problem has been all along.