Battery draining through ECU

[dlaing]

A few months ago I started having trouble with the battery getting weak.

I tested the charging output and it was very irregular, so I replaced the regulator and the charging became more regular,

but the battery became weaker and weaker.

I figure I had damaged the battery through use of an automotive charger or the bad regulator had damaged the battery, so I got a new battery.

The new battery still faded over night.

I tracked the fading to a 0.076 amp draw through the number one fuse leading to pin 17 on the ECU.

So, I figured I needed a new ECU, so I bought one from Carl Allison.

But it did not do the trick!

The amps dropped but only to 0.072 amps.

I tested with all relays and fuses disconnected.

To track down the problem I pulled the tank and disconnected almost every connector I could find.

I disconnected

the coils,

the fuel pump,

the engine position sensor,

the throttle position sensor,

the air temperature sensor and

the cylinder head temperature sensor (and I broke the plastic that the sensor screws into...warning this should only be finger tight and not beer cap tight).

I also disconnected the lines to the handlebar controls and lighting.

Everything I disconnected had no impact on the current, except for disconnecting the ECU.

The only thing I did not disconnect yet is the fuel injectors, and the safety diode (#48 on Carl's diagram).

The fuel injectors are a little difficult to disconnect...I will have to remove airbox.

I do not know where the safety diode is?????

Any ideas????

Does anyone have a schematic of the ECU?

[Mike Stewart]

Good one David,

 

Does not make any sense to me, I would think the ign switch would kill the power to the ECU via the ECU relay.

 

One thing you could try is with the ign switch off, take your volt meter and back probe (from the back where the wires go into the connector) each wire at the ECU connector (use a thin needle or pin to backprobe, do NOT use the meter ends) to locate which wire is causing the draw. Once you know which wire it is, it will hopefully lead you to the cause.

 

I don't know where the safety diode is, I would think it would be in the ECU but it could be wrapped up in the harness somewhere.

 

One of the weirdest parisitic drains I had was on a vehicle where the alternator B+ cable had rubbed through on a rubber coolant hose. There was just enough resistance through the rubber hose to allow a 75ma to drain the battery. Same problem as you, all fuses pulled, still had a draw.

 

Let us know your findings,

Mike

[Mike Stewart]

Well, I just reread your post and noticed that you could kill the drain by removing the #1 fuse

 

So, The ECU is powered all the time at terminal 17 (which is powered by fuse #1), I would still back probe the remaining wires to the ecu to see is it is an internal ecu problem or something outside.

 

I pulled out my old V11 sport harness and looked at the relay block, I found what I believe is the safety diode (#48 in the wiring diagram).

 

 

Good luck,

Mike

[dlaing]

Thanks for the replies, and a special thanks for uncovering the diode

Using the second ECU seemed to prove that the ECU is not the problem.

I hate back probing, but I am close to that point.

I don't think much current is going through the 17pin to ground...I think it is going off somewhere else, and then to ground.

I think I have also uncovered an error in Carl's and Guzzi's wiring diagram...will try to verifiy, but maybe it is the problem

[Mike Stewart]

I believe Carl just copies the wire diagrams from the owners manuel. I do not put alot of trust in the pin locations of the Guzzi diagrams. The one for my 2000 Jackal has just about every pin location off, so beware.

 

Back probing can be a pain in the arse , but it will do no harm to the connector if done properly. Should only take a few minutes to do the check and at least the ecu is out in the open. You should try this on some GM products

 

A 75 ma drain is like a small light bulb being powered (aprox. the size of a tail lamp bulb) but yet enough to kill the battery over night. These drains also tend to end the life of the battery early.

 

Mike

[dlaing]

I guess I should not knock back probing till I've tried it.(says the back probing virgin as he slinks off to the garage with his multimeter )

[Cliff]

I'm surprised the ECU draws power when off. I didn't realise pin 17 had permanent power. Didn't use it with My15M.

 

70mA, while thirsty for electronics in standby, should not drain a battery over night. Thats about 1Ah per night. Can't recall actual capacities - 20-40AH? I think your battery has problems.

[emry]

I agree with Cliff. 0.07 amp is a very small drain. Cars can have upwards of 0.5amps and still be considered acceptable.

[dlaing]

I'm surprised the ECU draws power when off. I didn't realise pin 17 had permanent power. Didn't use it with My15M.

 

70mA, while thirsty for electronics in standby, should not drain a battery over night. Thats about 1Ah per night. Can't recall actual capacities - 20-40AH? I think your battery has problems.

87837[/snapback]

At first it was taking a week before it got too low to start and then it got down to a few nights.

But oddly it also lost charge while riding...but every time I checked the charging system it was getting what seemed to be a good charge, although the charge maxs out at 13.8x Volt, apparently because of the Electrex Regulator...I have been thinking it may need a better ground

 

Perhaps the condition is normal and I really did need a new battery and now I may need to get the charging system running better.

The overnight voltage drops with the new battery were less than with the 17 month old battery.

If the condition is normal, how come I could let the bike sit for a month previously and then start it right up without a charge?

Could someone please do me a favor and with the key off, remove the number one fuse and tell me how many volts and or amps are going between the two terminals?

For Volts, I was getting a reading of something like nine or ten point something volts.

[dlaing]

I agree with Cliff. 0.07 amp is a very small drain. Cars can have upwards of 0.5amps and still be considered acceptable.

87844[/snapback]

Isn't 0.5amps like a dome light?

I know that will kill my car battery within 24 hours(from experience )

[Cliff]

For Volts, I was getting a reading of something like nine or ten point something volts.

87845[/snapback]

 

I think you should get at least 12V out of a good battery. My Breva falls to about 12V on turning on the key but that includes the headlight.

 

10V sounds like you've lost a cell.

[dlaing]

I think you should get at least 12V out of a good battery. My Breva falls to about 12V on turning on the key but that includes the headlight.

 

10V sounds like you've lost a cell.

87847[/snapback]

I don't mean across the battery terminals, but across the blade sockets of the number one fuse when it is out.

Both of the batteries seem to hold a good charge when the number one fuse is removed.

Although I have not tested the old battery much with that regard.

I am just about done giving the old battery a charge right now, and will see how it holds overnight.

Hard to tell as it will hover over 13V for a while after the charge.

The new battery reads a solid 12.82-12.84V for the past three days after getting a full charge followed by a five mile ride, followed by some probe testing.

Edit, I know the old battery was charging to over 12.65V

[Mike Stewart]

The spec. for GM cars is 25 ma, many cars come close to zero now with the new technology (after the 30 to 45 min computer time out).

 

I have let my Guzzi's sit for months with no problems starting so I know they don't have anything draining the battery. Now the BMW I had was a different story, it needed a battery every year.

 

Another good way to check to see if you battery is bad, is to disconnect it from the vehicle and let it sit for the amount of time you usually have the problem. In this case I guess it would be two days? If the vehicle starts up with it after that amount of time, then it is the draw causing the issue.

 

Once in a while I will get a battery that passes the load test but has an internal short that will take a day or two to bring it down and cause a no or slow crank issue.

 

Mike

 

 

 

Isn't 0.5amps like a dome light?

I know that will kill my car battery within 24 hours(from experience  )

87846[/snapback]

[dlaing]

And I have not had it die with the new battery, but I did watch the voltage of the new battery drop about 0.1V per night.

The older battery did drop faster.

[dlaing]

OK, I finally found a sewing pin, so off to back probe my mistress while the wife is away