Engine Harness Mounting and Routing 5.7L

76SeaRay

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Aug 24, 2017
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So, I am trying to sort out how the brackets and harness gets routed on my engine. This is an older harness from what I can tell since it has a square Thunderbolt IV Ignition Module as part of the harness. It appears the shift bracket gets attached to the Starboard Exhaust Riser and the harness plug then points in front of the riser. The TB IV module is attached to the Port Exhaust Riser. I believe the alternator wire was intended for an alternator high on the starboard side so it is too short to reach the alternator low on the port side. I can add length to reach the port side.

So, my questions are:

1) How or where does the alternator get routed to go from the harness Y to the alternator low on the port side?
2) The two small alternator wires were taped off in the harness as not used. Would that likely have been for a one wire alternator setup?
3) How or where does the circuit breaker bracket get mounted?
4) In the picture labeled "what" there are two questions, a) is this the cable to the starter and b) what is the part that looks like a big lug. Is it a lug or maybe a fuse? Where does it connect?

Alternator Wire?
Alternator Wire.jpg

Circuit Breaker Bracket
Circuit Breaker Bracket.jpg

What is This?
What.jpg

For reference here is the shift bracket. Does the circuit breaker bracket attach to this?
Shift Bracket.jpg

Thanks..............
 

Bt Doctur

Supreme Mariner
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Aug 29, 2004
Messages
19,386
The Red wire and the one with the plastic block get connected to the main battery post on the starter. The block is a fuse link protecting the wiring, Red is main system power, yellow/ W red stripe is for the solenoid
 

76SeaRay

Lieutenant Junior Grade
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Thanks. Can anyone tell me where the circuit breaker bracket mounts on a 5.7L and the routing of the wires to the alternator for an alternator mounted low on the port side? Any pictures?
 

76SeaRay

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Messages
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After going through a very large number of pictures and youtube video's, it appears that some engines mount the circuit breaker bracket above the fuel filter and some mount it behind the carburetor. I will have to see if it can be mounted above the fuel filter with the closed cooling system installed. As to the alternator wires, it appears they run forward on the starboard side along the rocker cover then down the front, over the top of the water pump to the port side, and then underneath the power steering pump to the back of the alternator. Looks like I might have to mount the closed cooling system first and then route the harness and circuit breaker mount.
 

alldodge

Moderator
Staff member
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Mar 8, 2009
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42,875
In most all cases the wires route on top the motor and down to the items. The big lug which goes on the starter post is a fuse. The fuse is inside the block and is there to protect the battery if the alternator shorts out

I would suggest connect the fuse to starter then route the wires the best you can to get others layed out. If need be add more wire to complete. Can also get a engine harness that is just wires and is cut to fit
 

76SeaRay

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Aug 24, 2017
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I think I will probably unwrap the harness and replace the alternator wires that are too short.. My harness was for the alternator mounted high on the starboard side and I am building the engine for the alternator low on the port side...
 

76SeaRay

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Thanks for sending that link... I will try to use the one I have and change out the alternator wires but if that doesn't work out or gets too involved then I can definitely use the link you provided.
 
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