Backwards Battery smoked ECU Starting Circuit... How to bypass... S2R800

[corey]

*** NOTE: Thread title changed to be more "search-friendly" in the future ***

SO.

You know that thing we all say we'll never do?
You know, mix up the battery terminals when putting a battery back in?
Yea.

After all the lovely work I've done pulling my side covers off and painting, Upon reassembly, and placement of my new battery... I managed to reverse the terminals.

Short and simple, bike won't start now (obviously i got the battery in properly now)

SYMPTOMS:
I'm 90% certain that the only thing that was fried in the process were the resistors for my turn signals.
I removed them from the system. I have the hyper flash now, but the signals do work.
Blinkers Work.
Headlight Works.
Highbeam Works.
Tail light Works.
Brake light works, both the front and rear controls engage the brake light.
When i turn the bike on, the fuel pump does engage. I get the "whirrrr".
Gauges turn on and sweep. They display the mileage that was on my bike when i last rode it, as well as the proper amount of mileage on the TRIP-O-Meter...
Neutral light works, oil light works, engine light works.
When turned off, the immobilizer light BLINKS as it normally did.
With all this, i'm relatively certain that I dodged a bullet, and that the ECU isn't fried... I hope.

Could it be the ECU?

With the bike on, in neutral, the kickstand up, and the the kill switch in the proper position, the start button does NOTHING.
No click, no crank, no nothin'

At this point I'll mention that I DID reroute my starter cable around to the other side of the motor.
I'm 99% certain that i wired it up properly, but i guess consider my epic fail with the batter, anything is possible.

Any ideas here guys? Any order of items to check / rule out?
Either I'm stupid and forgetting how to start a bike, or something else is TOASTED.  

I have a multi-meter.. but it's all fancy n shit and i can't figure out how to work it.

 

[Buckethead]

Everything else working sounds promising.

Have you checked your fuses?

[corey]

I have indeed pulled every fuse and they are all good.

HOWEVER, after some further searching on the forum, and some quick gap-bridging on the STARTER SOLENOID with an old shitty wrench... The tiny 803cc beast was awakened.

Starter solenoid is toast.

I appreciate your reply Buckethead!

God bless this forum and it's mountain of knowledge.

Thanks folks.

[ducatiz]

Just an FYI, if the gages sweep when key turned, that usually means the ECU is functional.

Glad you dodged it.

[Buckethead]

No prob. Just trying to rule out simple shit first.

Glad you didn't manage to make the beast with two backs it up too bad. 

[Howley]

Check the little cable that runs to the solenoid from the starter button. It's fairly easy to knock out.

[corey]

Check the little cable that runs to the solenoid from the starter button. It's fairly easy to knock out.

I'll definitely give this a check before i go buying a solenoid.

[suzyj]

Check the little cable that runs to the solenoid from the starter button. It's fairly easy to knock out.

There isn't a direct connection between starter button and starter solenoid.  It goes via the ECU.  The starter button is on an ECU input and the solenoid is on an ECU output.

When you press the button, it signals the ECU that you want to start.  It switches off the headlights, then turns on the solenoid.

Do you get a click when you press the starter?  That noise is the starter solenoid engaging (or trying to).

If there's no click, check the solenoid coil resistance.  If it's open, it's just the solenoid.  If it's good, you may have blown the circuit in the ECU that drives the solenoid, or else the back EMF diode between the solenoid and ECU.

If you look at the wiring diagram, you'll see the diode.  It's function is to protect the ECU from big negative voltages when the solenoid switches off and the field on the windings collapse.  If the battery is in backwards, this diode is a short between the battery -12V and the ECU solenoid driver.  It'll conduct a fair current.

Good luck!

[Howley]

Ok then check the plug that switches the solenoid. Doesn't matter where it comes from, if its not plugged in, its not gonna start.

[corey]

There isn't a direct connection between starter button and starter solenoid.  It goes via the ECU.  The starter button is on an ECU input and the solenoid is on an ECU output.

When you press the button, it signals the ECU that you want to start.  It switches off the headlights, then turns on the solenoid.

Do you get a click when you press the starter?  That noise is the starter solenoid engaging (or trying to).

If there's no click, check the solenoid coil resistance.  If it's open, it's just the solenoid.  If it's good, you may have blown the circuit in the ECU that drives the solenoid, or else the back EMF diode between the solenoid and ECU.

If you look at the wiring diagram, you'll see the diode.  It's function is to protect the ECU from big negative voltages when the solenoid switches off and the field on the windings collapse.  If the battery is in backwards, this diode is a short between the battery -12V and the ECU solenoid driver.  It'll conduct a fair current.

Good luck!

How loud should this click be? I thought on occasion when pushing the start button about 50 times that I heard a VERY faint click, but nothing like when trying to start with a nearly dead battery for instance.

Is this diode something that can be replaced if it turns out to be the culprit?

If it turns out that the starter circuit on the ecu is toast, is there a solution short of a new ecu? Could I bypass this circuit in the ecu by replacing the starter solenoid with a simple push-button relay and use that as a start button (if necessary)?

[corey]

Also, is there any way to absolutely confirm the solenoid is bummed?
Is there any way to confirm the hand switch isn't muffed?
What about this mysterious diode? Confirmable?
I would like to eliminate all possibilities before trying to bypass the ecu,.. and would LOVE to confirm the issue before dropping any cash...

[suzyj]

It's a pretty obvious click.

You can use a multimeter to diagnose.  For the starter button, disconnect the ECU body connector and put one multimeter probe into pin 28 on the plug (use a piece of thin solid wire a similar diameter to the pin in the ECU socket, like a component lead or something to get in there.  Set the multimeter to ohms and put the other probe on battery -ve.

The resistance should drop to less than 1 ohm or so when you press the starter button.

For the solenoid, disconnect the plug where it connects into the loom and poke your multimeter leads into the socket leading to the solenoid.  You'll need a pair of bits of thin wire to get in there.  Measure the resistance.  Mine is 4.5 ohms.  Significantly higher or lower than this and it's your solenoid.

The diode is a bit more tricky, as it's buried in the loom about 25cm back from the solenoid connector.  Here's a picture of that part of the loom in all it's naked glory:



To diagnose, disconnect your ECU body connector again, and set your multimeter to diode check.  Probe the solenoid connector going back into the loom, and you should see 0.6V or so with the red multimeter lead on the red/black wire side of the connector, and overrange the other way round.

Also check for continuity between the ECU body connector pin 1 and the red/black side of the solenoid connector, and between the other side of the connector and battery +ve.

If you need to bypass the ECU, pull the back off the ECU body connector, cut the wire to pin 1 (red/black) which goes to the solenoid and the wire to pin 28 (red/orange) which goes to the starter switch, and join them together in the back of the connector shell.  This will be the equivalent of putting a spanner across the solenoid to start, but a lot more convenient.  The only downside is that you're missing out on the ECU program which turns off the headlight first to give the starter more current.

[corey]

When you say "ecu body connector," do you mean the plugs going into the top of the ecu? And is there an easy way to identify what number pin I'm looking at?

[suzyj]

When you say "ecu body connector," do you mean the plugs going into the top of the ecu? And is there an easy way to identify what number pin I'm looking at?

Yes.  The ECU has two connectors on top - one for the body, one for the engine.  The body is the one towards the back of the bike, with blue innards.

Here's a picture to aid identification of pins:



If you pop the top off (link here:http://www.ducatimonsterforum.org/index.php?topic=56463.0) you can verify by wire colour, too.

Oh, and if you haven't already, download a pdf copy of your bike's owner's manual from the ducati website.  The last page has a wiring diagram, which you can blow up really big to see what you're doing.

[Howie]

Testing the solenoid itself is easy.  Remove solenoid.  Take your ohmmeter and connect it to the two large terminals.  From a battery, positive to one of the small terminals.  Ground to the other.  Polarity doesn't matter.  The ohmmeter should read almost zero.