'06, Tahoe Q7i, 5.7L Mercruiser, Start issue

Zeke150

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May 24, 2020
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Installed the battery yesterday after it being on a tender over the winter. Truthfully, I may have inadvertently swapped positive and negative wires. Got a spark. When I corrected the issue I get no radio, gauges, or engine turnover. The only thing that works is the blower, which doesn't require the ignition to be on. I have checked all around at the fuses around the engine and under the dash I can find. Found a blown 10 amp fuse under the dash that's connected to yellow wires, didn't think that would solve the issue anyway and it didn't. I can't find a red/purple wire with a fuse to replace under the dash. The only thing that it could be had like 5 prongs connected to it. Removed it but couldn't see where it is actually a fuse or not, photos attached. If this is a fuse who do I contact for a replacement, local marina? which is closed for a couple days over the holiday weekend.

I did some reading in the some other threads and saw the comment that the wiring goes from the battery, to a 90 amp fuse, to the 50 amp fuse to the ignition switch. Checked the battery with a voltmeter, checked good at 12 volts. The 90 amp fuse is in a precarious spot so I'll check that but will take some wiggling and will have to have my wife watch the voltmeter. I connected the voltmeter to the ground on the battery then to the the 50 amp fuse and get .219 on both sides. Since there is a reading on both sides does that mean its good? Or should the reading be higher?
 

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Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,453
That is a relay, nothing to do with power to the dash Go to the alt output Orange wire, you must see battery voltage there or the 90A at the start is blown If you go to the 50A circuit breaker you must see battery voltage on both sides
 

Zeke150

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May 24, 2020
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I tested the 90A with the voltmeter. Getting 12v on the battery side, .217v on the other side that goes to the 50A. I get .216v on both sides of the 50A. Is that 90A
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,453
looks like the 90A is done for . Given the location on some boats I cut away the Red wire and put it directly to the starter battery post, the Alt wire I crimp in a Maxi-Fuse fuse holder with a 60 A fuse. Thats more than enough to protect the alt wiring to the battery incase of a massive alt failure
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,348
Are you sure it’s the right way now ? Is your blower sucking or blowing ? Being serious !
when connecting your battery...getting a spark does not mean you have the terminals the wrong way round. Maybe sounds silly but I happen to know that some blower motors will run the other way if connected the other way on the battery. Same with some bilge pumps.
 
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