Weird symptoms of a Total Loss MSD Brain

[McDog]

I know that a dead Total Loss MSD brain doesn't spark.

Has anyone had one that wouldn't turn a motor over?

I have a setup on my roundnose that JSS did for me last year. I hooked it up and dialed it in myself. It works great.

I bought a backup brain on ebay last year and have since acquired the rest of the sysytem to put on my squarenose.

I ran all the wires EXACTLY the same as my JSS setup. I made sure every connection was soldered and shrink wrapped. Good wires. Good grounds.

The brain appears to be completely dead. No spark, no LED light....but wait. It will not even turn the starter when I hit the start button. Jumping the relay will turn it just fine. I checked it all with a multimeter. O ohms on the start switch when depressed so it should be fine. 12v coming from the on/off switch when on. I'm using a seadoo relay that Jetski Haven sold me. I switched it with my stock one with no difference.

I'm thinking I got screwed on the brain off ebay, but I've searched and no one else has posted about a ski not turning over because of a dead brain.

Ideas?

 

[Waternut]

I thought the start wires didn't go to the brain at all...Thought they went straight to the solenoid. I'll double check my ski's.

 

[SUPERTUNE]

The start relay has nothing to do with the MSD working. You need to make sure your start/stop assembly is not messed up too.
One wire off relay plug in goes to battery ground or a common ground, the other wire to 12v to be energized from the start switch. Try just using a jumper lead on it and touch it to the positive side of battery, should crank the engine over. If not, could be a bad relay, bad battery, bad main battery cables or a starter, but you stated if you jumped the poles it would crank over. So this leads me back to the start stop switch or a bad ground...

 

[Waternut]

Here is how my ski's are hooked up to the relay...yes it's crude but hopefully it's clear. Call me if you need a better explanation. lol

 

[McDog]

It's hooked up like yours John.

I checked the start/stop according to Clymer's. It has infinity resistance between the brown and red wires at rest, and 0 Ohms resistance when the start button is pressed. According to Clymer's it's working fine.

My ground is a new wire going straight to the battery. I know it is wired right because I triple checked it against my JSS setup. The brain is the only thing I can figure. Is it not possible that it's not allowing the circuit to complete?

 

[Matt_E]

Not possible.
The brain has absolutely nothing to do with relay/start function.
Touch the red wire from the starter directly to the positive battery terminal and see if it spins.

 

[McDog]

It spins if I jump the relay.

 

[Matt_E]

Take the wires off the big posts off the relay.
Measure resistance between the two big posts with and without start button pushed.

 

[Waternut]

Only thing that can be wrong is the relay itself or the wiring to the relay. I like Matt's test above...

 

[SUPERTUNE]

It spins if I jump the relay.

How are you jumping? Explain?
Get a jumper wire, connect to battery positive and energize the relay wire and if you do have a good ground and everything else right it will crank the engine.

 

[McDog]

Chuck, I'm jumping accross the two big relay posts with a screwdriver.

Matt, I'll try your idea tomorrow and let you know. Should be zero resistance with the button pushed, right? I'm done screwing with it tonight.

 

[Matt_E]

Is there an audible click coming from the relay when you push the start button?

 

[McDog]

no, nothing.

 

[Matt_E]

Make sure:
1. You have 12V to the small relay post (brown wire) when you push the start button
2. The other small relay post is definitively connected to ground.

If you have 1 & 2, then the relay is busted.

 

[SUPERTUNE]

Then do my jumper check...just like I stated and Matt has said you don't have a good ground or you don't have enough 12v (amps) feeding the relay from the start/stop switch.
OHM checks will NOT always work to test for being good when you try and feed power through wires and switches.

 

[McDog]

Thanks guys! I'll post the results tomorrow. Have a good night.

 

[Shifty]

You do have your lanyard in while doing this testing right? You must have during the Start/Stop switch test to get those results, just checking you still ahve it in there.

If your running the seadoo relay, pull the plug out and check voltage using both terminals of the plug while holding the start button down. If you vave voltage there move on to relay coil resistance to see if its shorted, one I bought from ebay blew on me. I don't know the resistance value for the seadoo coil but it should be similar to an OEM yamaha relay, not shorted.

I would say, if you have voltage at the relay plug while holding the start button, and you get nothing (no click) when plugged in, your relays bad.

 

[McDog]

Hooked it back up today, but put my other battery on it and it works fine. I guess my battery was about dead. It would turn the starter with a straight jump but I'm guessing it couldn't overcome the resistance to switch the relay. The LED light works too!.....BONUS. (It didn't work on my other brain) I haven't checked for spark yet but I'm keeping my fingers crossed.

LED question: It lights up over a span of 20 degrees. Which point do I assume to be correct? The point where it first lights up or somewhere in the middle?

 

[Shifty]

Assuming this is a digital unit: The light will remain on for some time during the rotation but the point where it first lights up is where your degree reading is. Turn the coupler slowly clockwise (as if the engine was running). As soon as the LED illuminates consider this your static timing (when your ignition will spark).

 

[McDog]

Thanks everyone for the help.

I just realized that I have a Kawasaki pickup plate for it. I knew something was amiss when it seemed to torque the plate when I tightened it down. Then I couldn't adjust the advance any less than 38 degrees. I might be able to "adjust" it to fit, but I'm thinking I should find a Yamaha plate instead....the saga continues.