496 no start issue

[chartersj]

I recently put the motor back in my boat and having a hard time getting it to roll over. The motor has a relay for the starter and not a starter slave solenoid. I have power from the battery to the starter, but no power to the starter solenoid when I turn the key to start. I have power to the starter relay (red/purple), I get good continuity from yellow/red at the key to the relay. I have checked through the neutral safety switch at the gear shifter and shift cable at the motor. I crossed the terminals at the relay and starter would roll the motor. I swapped relays with the fuel pump relay and get the same symptoms. I do not get a click or sound of any kind when I turn the key from on to start to try to roll the motor over. Lanyard is on as well. Looking for advise on what to check next. Thanks.

 

[alldodge]

I get good continuity from yellow/red at the key to the relay.

Good, power is coming from the key to the slave relay (yellow/Red), but it also needs a ground connection (Black) on the other side of the relay, so its energized.

 

[chartersj]

Good, power is coming from the key to the slave relay (yellow/Red), but it also needs a ground connection (Black) on the other side of the relay, so its energized.

Ok I wasn't sure if that was a ground or not. It is black with a yellow tracer, which seems to go from the relay, through the shift cable switch on the motor , and then to the pcm. Does it get ground through the computer?

If So, I am also having a (sporadic) problem with the key on beep which the beeper gets 12+ purple from the key and gets it's ground from the pcm. I wonder if these problems are related...

 

[alldodge]

It is black with a yellow tracer, which seems to go from the relay, through the shift cable switch on the motor , and then to the pcm. Does it get ground through the computer?

Something is not correct, lets start with your title

496 no start issue

The 496 was not built in 1996

black with a yellow tracer,

That does not go to a starter solenoid or relay

Black/yellow goes to a knock sensor

 

[Fun Times]

I know you're getting continuity from yellow/red at the key all the way back to the relay but are you getting full 12 volt power when you turn the key from on to start at the key and all the way back to the relay? That's what you also need to know/verify.

Does the Red/Purple wire at the back of the key switch have and hold 12v power when activating the key switch enough that the key will transfer 12v to the Start Yellow/Red wire?

Also try jumping the 3 wires at the back of the key switch to see if it will power up normally. (Purple, Red/Purple, Yellow/Red)

With the key on/held to start, Wiggle the main 10 pin wiring harness at the engine and any other wires to the system.

 

[chartersj]

The motor is a 2007 (1A074806). I will verify tomorrow but I am quite certain the 4 wires into the relay was red/purple, yellow/red, both which are slightly larger gauge, and black/yellow, and yellow/black. The yellow/red from the key goes to the cannon plug and switches to yellow/black and then to the relay.

I will verify the voltage again in the spots mentioned.
I will also add the everything else works fine, at the dash and also fuel pump turns on and will do it's cycle when key is turned on.
something strange I noticed when I turn the key from on to start the volt meter will drop a tiny bit indicating it's picking up a slight draw or load

 

[chartersj]

Here is the starter relay. My memory was correct on the wire colors. I do think my problem is with the black/yellow ground. My manual does not have a wiring diagram for this motor in it which is odd.

 

[chartersj]

Did some voltage checks,,, my battery voltage is 12.4v. Normally 12.7 but down a little because I have been working on the stereo and lights as well. I get 12.4 to the red/purple at the relay when I turn my battery switch on. Then with the key to the start position, and held, i get 12.2v on the yellow/black at the relay, which is the yellow/red from the key it just changes color through the cannon plug to the motor harness. I tried another relay from a local shop and no difference.

 

[chartersj]

I have read online that merc changed to the relay system over the slave solenoid for the year 2007 496 models up, and the wiring harness changed as well. Where could I find a wiring diagram for it? My manual doesn't have one in it.

 

[alldodge]

Guess I would need to find which side of the coil is ground. If the Black/Yellow is ground then its open because of the voltage being measured.

Have not been able to find the wiring diagram, but also don't see the ECM being used to create a ground after 12V has been applied to the other side of the coil

 

[chartersj]

Guess I would need to find which side of the coil is ground. If the Black/Yellow is ground then its open because of the voltage being measured.

Have not been able to find the wiring diagram, but also don't see the ECM being used to create a ground after 12V has been applied to the other side of the coil

Black/ yellow would be ground because i got continuity from the yellow/Black to the yellow/red at the key switch. I'm not getting voltage on the black/yellow, and I am not certain the ecm grounds the black/yellow I just got continuity from it at the relay to one of the blacks going into one of the ecm plugs and to the shift switch. On the other side of the shift switch is another yellow/orange which I have not traced yet. It does seem like an open circuit on the ground to the relay. Could I make a temporary jumper from the negative post on the battery to the black/ yellow for testing purposes only or would there be any risk of doing damage to the ecm?

Thanks for looking for a wiring diagram for me, it would be a big help to have a copy of that. I'm open to any suggestions and brainstorming.

 

[Bt Doctur]

Is this an inboard? there is a transmission switch tied into the slave solenoid/relay using the black/yellow

 

[Bt Doctur]

click to enlarge

 

[Fun Times]

We're not going to have any access for an 2007+ wiring diagram due to in 07 Merc went to using a specialized paper type binder made for service technicians to be able to take out to the boat while working on it in order to follow along easier, write and erase on it, get it wet and dirty which is easily cleanable, etc..

Here are all the ones I could locate for the 496/8.1l engines but there may be others so a dealer may have to look yours up and order it for you or get the part number from them to search it out online yourself, [h=3]MerCruiser 8.1 496 Non-Integrated ECM Harness & Starting Wiring Harness Diagram [/h] [h=3]MerCruiser 8.1 496 DTS & w 10 Pin Connector Removed Wiring Harness Diagram [/h] [h=3]MerCruiser 8.1 496 MAG DTS & MAG Non DTS with Emissions Wiring Harness Diagram [/h] [h=3]MerCruiser 8.1 496 DTS & Can Bus to 14 Pin Connector Wiring Harness Diagram [/h] [h=3]MerCruiser 496 8.1L Mechanical Engine 14 Pin Connector Wiring Harness Diagram [/h] [h=3]MerCruiser 496 8.1L DTS Engine with 14 Pin Connection Wiring Harness Diagram [/h] [h=3]MerCruiser 8.1 496 Non DTS 10 Pin & Can Bus to 14 Pin Wiring Harness Diagram [/h] https://www.ebay.com/sch/i.html?_fr...iser+496+Binder+Wiring+Diagram&LH_TitleDesc=0
[h=3]Since I'm in here trying to locate some, The ones below are other engine models for other future reference's here on iboats,
MerCruiser 5.7 Carbureted Thunderbolt V & 5.7 TKS 10 Pin Wiring Harness Diagram[/h] [h=3]MerCruiser 5.0 Bravo & 5.7 Alpha Bravo Carbuteted 14 Pin Wiring Harness Diagram

MerCruiser 5.0 5.7 Alpha with Emissions Control & A/B Wiring Harness Diagram

MerCruiser 5.0 5.7 DTS with Emissions Control Wiring Harness Diagram DEALER [/h] [h=3]MerCruiser 4.3L MPI Engine Wiring w 14 Pin Connector Wiring Harness Diagram [/h] [h=3]MerCruiser Black Scorpion & with 14 Pin Connector Wiring Harness Diagram DEALER [/h] [h=3]MerCruiser 5.7 6.2 Towsports Gen 2 Cool Fuel & w 14 Pin Wiring Harness Diagram [/h] [h=3]MerCruiser 4.3L V6 14 Pin w 16 Pin Trans & 4.3L MPI V6 C Wiring Harness Diagram[/h] [h=3]MerCruiser 3.0L Carb Alpha & 3.0L TKS Alpha Wiring Harness Diagram DEALER [/h] [h=3]MerCruiser 4.3L A/B 5.0L A Sterndrive & 4.3L A/B 5.0L TKS Wiring Harness Diagram

MerCruiser 5.0L 5.7L 350 cid 6.2L Bravo w 14 Pin & DTS Wiring Harness Diagram

MerCruiser 5.0L 5.7L 6.2L Alpha & 5.0L 5.7L 6.2L Bravo Wiring Harness Diagram

I don't have PCM manual number 33 which usually is available online somewhere but just for quick reference the ECM 555 manual 36 also shows a Yellow/Black wire inline of the starting system too, http://boatinfo.no/lib/mercruiser/ma...er36.html#/106[/h]

 

[alldodge]

Ebayer bigmanualwarehouse is found a real nitch
Buy the manual from Merc and then sell the pages for $9 each, wouldn't take a lot of pages to pay for it self, and its all 100% legal becuase there is no copying, all original

 

[Fun Times]

Try jumping the relay to see if the engine cranks over.

You're getting power up to the relay but noting out to the starter it seems.

But if you're getting intermittent key/power up signals losses too then you ought to have an power interruption somewhere else leading into all the relays whether it be + or - side It seems.

 

[chartersj]

The boat is a bravo set up. Any wiring diagram I have seen that has the solenoid vs relay has different color combination wiring for some things.

The boat side of the cannon plug is a 10 pin, and I see a mercruiser adaptor has been used to convert from 10 pin to the 14 pin on the motor side.

Going through the diagnostic manual 36 that funtimes posted I was able to look up a few codes that I got with a rinda scan tool last fall before I pulled the motor. The motor was running at 100% available power at the time with no warning beeps but would of come up sometime within the 20 hours I put on the motor last summer. One that stuck out to me was 151 - fuel pump relay circuit, which says it could be a wiring, connector or relay problem. Also 210 - overspeed neutral which says bad shift switch, engine exceeded specified rpm in neutral. Then there was 15 - MAP sensor circuit, 40 - Manifold air temp circuit low, 77 - camshaft sensor fault, and 132 crank position sensor fault, all say wiring or sensor problem.

The engine will crank over if I jumper the red/purple and yellow/red. and I get good voltage from the key to the relay, it must be something I am missing on the ground side of the relay.

 

[chartersj]

I hooked up vessel view to the motor today and no new faults. Also when I put volt meter across the yellow/Black and black/ yellow at the relay I get 7 volts. When I put the negative lead to the negative battery post i get 12.3 or same as the yellow/red at the key.

 

[Bt Doctur]

click to enlarge

 

[alldodge]

I hooked up vessel view to the motor today and no new faults. Also when I put volt meter across the yellow/Black and black/ yellow at the relay I get 7 volts. When I put the negative lead to the negative battery post i get 12.3 or same as the yellow/red at the key.

Bad ground