MC-1 won't raise via trailer / out switch. Trim works up and down...

[Hangar3]

I have a 1977 Starcraft SS with a MC-1 / 140 merc and during the restoration of the dash panels we have somehow lost the trailer or out function of the outdrive. I temporarily adjusted the trim sensor to allow the tilt function to bring the outdrive up far enough for safe trailering but that is obviously not the solution. I get nothing when trying the out / trailer switch either by itself or in combination with the tilt up switch, which is the way it used to work. Looking at the wiring, the combination of switches and lights doesn't really make sense to me but I have not really studied it with a diagram (source ?) in hand. Any short cuts to trouble shooting the tilt / trim function of this outdrive would be very much appreciated.

 

[Bondo]

Any short cuts to trouble shooting the tilt / trim function of this outdrive would be very much appreciated.

Ayuh,.... Welcome Aboard,..... Yer problem is exactly opposite the most common problem, the trim switch, 'n it's rotten wires,....

The dash tilt switch by-passes the trim switch on the drive, 'n directly powers the solenoid at the pump,.....

 

[Hangar3]

Ayuh,.... Welcome Aboard,..... Yer problem is exactly opposite the most common problem, the trim switch, 'n it's rotten wires,....

The dash tilt switch by-passes the trim switch on the drive, 'n directly powers the solenoid at the pump,.....

Thanks for the welcome and the tip. Looks like I need to see if I'm getting 12 v out of the trailer / out switch headed towards the solenoid and if not, why not... That make sense that the trim limit sender is by passed by the trailer / out switch...

 

[Grandad]

Since your problem is not the usual limit switch, have a look for a reverse lockout switch. My '72 has a small micro-switch that will stay activated if debris settles into the mechanism, which it can easily do when re-fitting. Sorry, this is the best picture I've got. It's a 1 minute fix with a toothpick or small brush. Blue arrow points at the switch, red arrow is where the debris will accumulate.

Mine failed after I idled in the water waiting an hour for my turn to pull out at a busy launch. Then it wouldn't tilt to pull out. What a pain. After dragging it up the ramp on the trailer, I mechanically disconnected the cylinders for the trip home with the outdrive hoisted on ratchet straps. I knew it wasn't the trim limit switch cuz I'd already bypassed that sucker, but didn't even know about the reverse lockout until I googled the schematic. - Grandad

 

[Hangar3]

Grandad, Thanks for that ! I'll have a look. I don't recall seeing a micro-switch located near shift plate although there is a micro-switch, that is a lockout of some sort, on the shift lever control (yellow wires) that I thought would prohibit starting while in gear. The real trouble lies in the PO or his mechanic, having their way with some of the wiring. I have the service manual # 2 and will try and figure out what's correct and hopefully, what's not but that switch being fouled would sure make life easy.

 

[Grandad]

Do you have a single solenoid system? If so, here's a schematic that I used to sleuth mine. Apparently as "old" as my '72 is, it conforms to this diagram identified as having a "Late Bushbutton" circuit. I also have an "Early Pushbutton" diagram should anyone need it. - Grandad
View attachment Merc Trim 1 Sol Late PB.pdf

 

[Hangar3]

Do you have a single solenoid system? If so, here's a schematic that I used to sleuth mine. Apparently as "old" as my '72 is, it conforms to this diagram identified as having a "Late Bushbutton" circuit. I also have an "Early Pushbutton" diagram should anyone need it. - Grandad

Mine is the 2 solenoid but the switch side of this diagram should sorta remain valid and worthy of review for a possible solution. Thanks !