Chasing Electrical Gremlins

[johnebquick]

OK, Now I'm chasing electrical gremlins.

I fixed the no start problem and verooooommmm, it started right up.
Now my trim tilt is not working. I don't know???? It worked two days
ago. I know its somthing I did in the rewiring if the dash.

My question is.....
I have power to the T/T pump through the solenoids down to the wire
harness plug. From there the plug harness has only 3 wires. Red -
green - blue at the plug but it also has an additional wire not being used.
All 4 wires go up to the trigger switch on the throttle. I'm not sure if the
problem is in the switch or not. I'm going to bypass the switch and
use a jumper from the red to blue or red to green to see if the pump operates.
If so, I have a bad switch and I'll probably mount a new on on the dash
and bypass the trigger switch on the throttle. If not I have to start
troubleshooting the T/T pump itself.


What does the purple wire do on the 4 wire set up from the throttle to
the T/T pump?
There is......
__________________
Green is the down
Blue is the up
Red is the power
Purple is ?????

The purple wire is not hooked up to anything back by the T/T pump.
What is this for?????

[johnebquick]

I think the 2 blue wires tied together and the purple wire are high and low limit switches for the trim/tilt. Are they needed? I have trim tabs also. So once I get the motor where I want it, I would use the Trim Tabs more often.

[Proheat]

I think the 2 blue wires tied together and the purple wire are high and low limit switches for the trim/tilt. Are they needed? I have trim tabs also. So once I get the motor where I want it, I would use the Trim Tabs more often.

Definately need the limits(especially the high limit) to prevent you from tilting the drive unit too high and basically twisting the universal joint that goes from the engine to the outdrive.

[johnebquick]

Just did some more troubleshooting and found that from the 3 prong plug up to the switch on the throttle, is open. I have no power going to the switch.

I stripped the wires out of the throttle and pulled the extra 10ft of wire up to a 2 position switch on the dash. I rewired the blue green to the top and bottom of the switch and made a jumper from my positive lead that's always hot on the Amp gauge to the center of the switch. This was to prevent from running 30ft of wire to energize the switch.

It never had the up or down limit switch wired in. Now I know what it is and how it's wired, I will start the search to locate them and replace the limit switches and sending unit.

Another project, Another day !!!!

John

[johnebquick]

I found these schematics of the wiring diagrams of the Mercruiser 5.7L wire harness
and gauges. I thought I would share them for everyone to use.

I did solve my problems and figure out what all the "wires" were and the only thing I have
left to wire up is the trim sender to the gauge and the high limit switch. Both sets of wires
are there and wired through the hull but are corroded off and I have to run new jumpers to
see if they even work. Another time. I want to get in the water for the first time this year
on Friday. I will be careful with the trimming of the outdrive. I also have Trim Tabs and now
have them working for the first time.

Thanks and Enjoy,

John