Trim and Tilt on 2008 Yamaha 300 HPDI

[boscoe99]

OK , maybe I put something into this that did not belong.

I said in a post above that if both the old and new relay work in a different motor but not in his.

I am not sure he said that, but he did say the new one did that

I am confused now also.

Here is what I think that we know.

1. The trim/tilt motor works fine when powered directly. Positive to the blue lead and negative to the green lead and vice versa.

2. Two relays; his and the one that he got ahold of.

3. Both relays work on the other motor. Both relays don't work on his motor.

"So, I got ahold of someone with the same motor and swapped out relays between motors. The relays that didn't work on my motor worked just fine on the other one."

"The relay on the motor right now has been tested on another outboard and it worked fine. When installed back on mine its back to the clicking."

[boscoe99]

Trouble shooting in person can be hard. Trouble shooting over the innerweb, well...

[boscoe99]

Mr. OP, when you removed the relay from your motor did you disconnect the black ground lead at the relay or at the ground connection point on the motor?

[Txbass12]

OK , maybe I put something into this that did not belong.

I said in a post above that if both the old and new relay work in a different motor but not in his.

I am not sure he said that, but he did say the new one did that

come to think on it some more, maybe the original relay was bad, and the new one was wired up wrong when put back in?

Original relay tested fine on other motor along with the other one. Replacement relay was wired up correctly. Its been removed and replaced a few times now in trying to figure this out but I did confirm proper wiring. I did take a picture of original wiring to reference just in case too. I didn't get time yesterday to work on it but need to get back at it and hope for the best for the upcoming weekend.

[Txbass12]

I gave up after getting the same results of the relay constantly clicking with everything else seeming to test fine. I ran it into a shop and a diode was mentioned. There is a diode in the wiring harness that the Sb, Lg and B run to. It tested bad and when temporarily bypassed the relay operates the trim motor as it is supposed to. There are no values stamped on the part or in the wiring diagram so hoping to replace the part with one off of an older Yamaha rather than a Radio Shack diode. Evidently this diode is part of the harness and is not available on its own.

[99yam40]

if this diode is in the control circuit, it cannot be a very high current diode since it just picks up the relay and does not carry the T&T motor current .
and it is only in a 12 volt DC circuit, so trying some diode should not hurt

I always thought most diodes failed shorted not open.
good find

[boscoe99]

I gave up after getting the same results of the relay constantly clicking with everything else seeming to test fine. I ran it into a shop and a diode was mentioned. There is a diode in the wiring harness that the Sb, Lg and B run to. It tested bad and when temporarily bypassed the relay operates the trim motor as it is supposed to. There are no values stamped on the part or in the wiring diagram so hoping to replace the part with one off of an older Yamaha rather than a Radio Shack diode. Evidently this diode is part of the harness and is not available on its own.

zdio.jpg
Does it look like the one below?
zdiod.jpg

[99yam40]

it that is it then it is more than just a diode , probably need to find the correct part

[fairdeal]

This is very interesting - I'm still trying to process it.

The OP's testing showed that the problem was with actuation of the relays,
so either

- neither coil pulled in (although didn't I read it audibly 'clicked' ?)

- both relays pulled in simultaneously - so there was power on both motor leads,
no ground

Since the diode on each control lead connects to ground,
what diode failure scenario explains this?

the diodes are only there for 'induced current protection'

diode fails open - doesn't affect for relay activation

diode fails shorted - why doesn't a fuse blow ?
and how does that affect both relays?

[boscoe99]

I am not understanding it either. Don't see the diode assembly being part of the problem. Relays will work on the bench without the diode assembly being involved.

[boscoe99]

it that is it then it is more than just a diode , probably need to find the correct part

Diode assembly is not available as a spare part. Either fabricate one or find a part out of a used harness.

[boscoe99]

This is a puzzle to be solved. Can we get another test please?

Relay not connected to its power supply and the control circuit disconnected at the connector.

Jumper a battery directly to the relay posts. Heavy wire. Relay connected to the power trim and tilt motor.

Momentarily apply battery power to the light green wire. Does the motor trim down?

Momentarily apply battery power to the sky blue wire? Does the motor trim up?
ztest.jpg

[99yam40]

This is very interesting - I'm still trying to process it.

The OP's testing showed that the problem was with actuation of the relays,
so either

- neither coil pulled in (although didn't I read it audibly 'clicked' ?)

- both relays pulled in simultaneously - so there was power on both motor leads,
no ground

Since the diode on each control lead connects to ground,
what diode failure scenario explains this?

the diodes are only there for 'induced current protection'

diode fails open - doesn't affect for relay activation

diode fails shorted - why doesn't a fuse blow ?
and how does that affect both relays?

could they be Zener diodes that bleed excess voltage to ground?(voltage spikes)

[Txbass12]

boscoe99 The diode on my motor looks smaller than the one in the picture you posted. It is approx 1" long by 1/2". As soon as the diode was bypassed the trim worked as normal. A used diode off of a parts motor was installed and the trim motor works just fine from all switches on the boat and the one on the side of the motor. Odd thing for sure but it appears to be fixed at this point. It was located in the harness on the back of the block behind the black plastic shield.

[boscoe99]

The photo might be making my diode assembly look larger than it is. I just measured the one that I have, which came from a parts motor as well. It is ~ 1 1/8th X 5/8ths X 3/4ths.

Glad that you found your problem even if I am not understanding it.