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1998 mercury 200 efi, my motor will trim up but not down

Easiest first step is to swap relays. After swapping, try to trim down. If down works now and up doesn't, your down relay needs to be replaced.
 
Relay swap is the easy first one, agreed. One thing worth knowing on these though. On the permanent magnet trim relay setup the two heavy motor leads get switched to either positive or ground to make the pump run either direction. So down needs two things working, the down relay putting 12 volts on the green lead, and the up relay grounding the blue one. Either one goes bad and you lose just the one direction...

Two checks with the key off. Pull the heavy leads off the relays and ohm each one to ground. Both should have continuity. The one that reads open is your bad relay. Then meter the blue lead while someone pushes up, you should see battery voltage. Same on the green lead pushing down. Nothing at green means the fault is upstream of the pump, switch, harness, or that relay...

If you do get 12 volts at green and it still won't turn, jumper the pump motor straight to a good battery and see if it runs down. Runs on the jumper but not on the switch, it's wiring or relay. Won't run either way, the pump motor is done...

FWIW I chased one of these for a while and it turned out to be the green lead corroded through inside the insulation where it passes the clamp. Looked fine from outside. Not saying that's yours, just don't trust a wire because it looks good...

What do you hear when you push down, a click up at the relays, or nothing at all? And does it go down off the switch on the cowl if yours has one...

Thanks
 
Miles2000 said:
Relay swap is the easy first one, agreed. One thing worth knowing on these though. On the permanent magnet trim relay setup the two heavy motor leads get switched to either positive or ground to make the pump run either direction. So down needs two things working, the down relay putting 12 volts on the green lead, and the up relay grounding the blue one. Either one goes bad and you lose just the one direction...
Click to expand...
What is the permanent magnet?
 
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