Don S: Merc 888 wiring diagram request

[dc2lv2atl]

I need a ignition and dash wiring diagram for a 1973 Mercruiser 888 SN:3440268. Don S posted a link for me last month and I didn't see it until now. The link is no longer valid. It was from vol #1, Don could you please repost the link for me. Thanks.

 

[Don S]

Re: Don S: Merc 888 wiring diagram request

Got a link to that thread so I know what I called the picture?

 

[dc2lv2atl]

Re: Don S: Merc 888 wiring diagram request

Got a link to that thread so I know what I called the picture?

The URL is:
http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=24;gtid=1114163
I really need to see how the ignition and dash gauges hook up to the wiring harness.

 

[dc2lv2atl]

Re: Don S: Merc 888 wiring diagram request

It appears that the previous owner replaced the original (dash-side) harness with something different. It has the standard 9-hole configuration, but the wire colors are different. It time to break out the ohm meter and check for continuity across the plug. Does anyone know of a better way to figure out what is what?

 

[Don S]

Re: Don S: Merc 888 wiring diagram request

What are you trying to figure out? If it's the starting problem, the start (cranking) circuit should be a yellow wire coming off the ignition switch and going to the start solenoid (small terminal).

 

[dc2lv2atl]

Re: Don S: Merc 888 wiring diagram request

What are you trying to figure out? If it's the starting problem, the start (cranking) circuit should be a yellow wire coming off the ignition switch and going to the start solenoid (small terminal).

I figured out the wiring harness configuration by using my trusty old multimeter. I understand the yellow wire comes off the ignition switch (Battery Terminal), the white wire comes off the ignition switch ( Accessories terminal), and the red-white wire comes off the ignition switch (ignition terminal). I have a 4 terminal ignition switch with the last terminal in the middle and it is marked ST for starter. What I don't have is any more wires under the dash. I can easily run a wire from the starter to the terminal, but I wasn't sure.

 

[Don S]

Re: Don S: Merc 888 wiring diagram request

I see why it doesn't work, you have the wires on the wrong terminals of your ignition switch.
The old switchs like you have had 4 terminals
Marked I,A, B, C.
B= ignition should be the white wire and should go to power the instruments and put power to the + side of your coil. I is your battery power and should be the 10ga. red or red/white wire.
C is for start circuitt, and should be the yellow wire.
A is for accessory, and isn't used.

Now, if you have a new style switch, It would be different. I would be ignion (White wire), B would be battery (Red wire), ST would be start (Yellow wire) nothing on the A (accessory) terminal

 

[dc2lv2atl]

Re: Don S: Merc 888 wiring diagram request

Thanks Don. I'll get on it right away.

Ron
Las Vegas, NV

 

[dc2lv2atl]

Re: Don S: Merc 888 wiring diagram request

Don:
Thanks, it works like a charm.