Offshoreonly.com - Merc 600 SCI IAC 1 Amp Fuse Install

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Right - which is the "negative" (PCM) side of the IAC circuit. (white w/ blue tracer)

Quote:

Originally Posted by 575cat (Post 4538324)

Talked to Eddie Young a couple weeks ago and he says the red w blue tracer is already fused along with some other components so I will put it on the white w blue tracer according to his diagram .

Quote:

Originally Posted by ALL_IN! (Post 4538191)

Hey, GF?, I've been looking at the wiring diagram tonight. The PCM controls the ground for the IAC (as well as other controls). The 12v source is shared with the boost controller. This 12v source is supplied through the fuse from the Main Power Relay. I don't see how a 1A fuse on the 12v source is going to to protect the PCM, as they are not connected. A high amperage situation on the negative side of the IAC could result in damage to the PCM.

Would you further explain your logic. I appreciate it!

Terry

Actually, you can't have high amperage on the negative side of the IAC without the 12 volt power source. The damage to the PCM occurs when the IAC coils melt and create a direct short between the 12v power source, which is on a 20AMP fuse and the PCM which is ground when it is trying to move the IAC. I've tested many failed IACs and they don't short to their housings, only across the two leads. It technically doesn't matter which IAC lead that you put the 1 amp fuse on but it's best practice to fuse the positive side of a circuit.

GF?

Quote:

Originally Posted by VoodooRob (Post 4520208)

From what I have gathered from this site, low voltage will destroy the PCM, 10 or 15 amp lets too much thru, 1 amp will save the PCM. Am I correct people in the know?

Correct.

Quote:

Originally Posted by 575cat (Post 4520190)

Do you think a 10 or 15 amp fuse would be better ?

I think you will need to keep the 20 amp fuse because that circuit supplies power to the boost controller as well. Plus, even a 10 amp fuse won't protect the PCM from an IAC failure.

GF?

Just some of jist --- The red / blue wire is the IAC connection / feed to the IAC by pass valve. That also is spliced up to the area of 4 fuses 20 to 25 amp.

The IAC -- white / blue wire goes to the PCM connector B. -- That's the middle connector on the PCM

Had a PM asking, so I wanted to just post a followup, this is what I made for mine. I should have made the harness shorter, but it was a little easier to assemble at this length.

1 Amp fuse.

[ATTACH=CONFIG]567621[/ATTACH]

ALL_IN!, nice setup, would you mind sharing the part number / source of the connectors you used? I've searched in the past and never could find the male/receptacle side.

Thank you,
GF?

It took me a while to find them too. ...quite a while, in fact. I work in the auto industry, so I had to reach out to some of my resources for some part numbers.

The connector bodies are ....
AMP SSC-2 Black Female
AMP SSC-2 Black Male

Usually, you have to buy like 5 million of them to get the 4 I needed. But I found a website....
www.CycleTerminal.com
...that sells smaller quantities, and even has kits with the terminals, locks, and seals. I already had the proper crimper for the metri-pack / superseal type terminals.

About $20 or so in the two that I made. The 1 amp fuses are also hard to locate, locally. So Amazon was the source.

Quote:

Originally Posted by Got Freedom? (Post 4556070)

ALL_IN!, nice setup, would you mind sharing the part number / source of the connectors you used? I've searched in the past and never could find the male/receptacle side.

Thank you,
GF?

I could not find 1 amps also so I went with 2 amp .

Try Amazon. I believe you would be safer with 1 amp vs 2 amp. But I don't know if anyone knows for sure. The 1 amps have evidently been holding up to the IAC amperage draw under normal conditions.

Quote:

Originally Posted by 575cat (Post 4556695)

I could not find 1 amps also so I went with 2 amp .