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Boat Tilt/Trim Relays


#1

I was able to determine I had a bad relay on my boat. I could move the motor down but not back up. Switched the relays and I could move the motor up but not back down. The relays are 5 pin 12v 30a relays. I was able to find two different relays. 1 at NAPA and one at Orielly’s. When I installed the new relays, they both just squeal. They feel like they are activating but there is a high pitched squeal coming from both of them. I did get the motor to move up and down 1 time randomly but I cannot get it to work again. Any help would be greatly appreciated.


#2

Without seeing the boat in action, or hearing the described problem, I am going to give you my best guess.

The noise you are hearing is most likely the electromagnet switch inside the relay quickly engaging and disengaging. There could be a number of things that cause this, but if the noise is coming from the relay, that’s my best guess. The way a relay works is, you can use a low current trigger, providing power and ground to pins 85 and 86 of a relay, to create a connection between 30 and 87 (see attached image)

Bosch%20Relay%20Pinout

30 and 87 are capable of carrying 12v at 30 amps (normally). With what you are describing, a few things may be happening.

  1. You have a bad ground for 85, or the switch isn’t supplying enough current for 86.
  2. The relay you pulled out is configured differently than the one you put in, which means it’s no longer wired correctly.

This is all assuming you’re using a relay that looks like this:
16%20AM

I hope this helps you diagnose the problem further.


#3

Poor connection and a bad relay. I think one of the new relays I got was bad and the contacts at the battery were corroded. I cleaned up the connections at the battery with a wire brush and put in a different relay and it works like a champ. Thank you for the help.