CAJ Innovations Forums - MyECU current draw when switch is off.

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97 Sport1100i My16M MkVII
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MyECU current draw when switch is off.
07/25/11 at 07:04:48

My Battery discharges to an unusable state in a few days unless connected to a battery charger while not in use. I attached a current meter in series with the battery and discovered that with the ignition switch off, and the Run/Stop switch on, the meter is showing ~40mA current flow. I can't test with the Run/Stop switch off, because a relay starts cycling at about a 1sec rate. I am uneasy about leaving the switch in this state long enough to find out which relay, but I suspect that it is the ECU relay. Does anyone know what is normal current drain with the ignition switch off?

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Re: MyECU current draw when switch is off.
Reply #1 - 07/25/11 at 07:09:45

There should be no current draw.

Which ECU do you have.
Most late bikes have the instrument panel powered. Take a measurement with the ECU disconnected.

Either way 40ma is going to be a discharge of 1AH per day. Your battery should be around 20Ah so if it is draining that quickly I suspect you battery has problems.

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Re: MyECU current draw when switch is off.
Reply #2 - 07/25/11 at 07:18:38

I have a My16M in a '97 Sporti. With the ECU disconnected, there is negligible current drain (it may be just the zero setting of the current meter). I disconnected the ECU because pulling the ECU fuse was the first indicator that the current drain was there. By the way, I am using pins 10 and 15 as the O2 sensor inputs ( I have two O2 sensors installed). I disconnected those external wires and saw no change in current with the ECU still connected.

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« Last Edit: 07/25/11 at 07:24:10 by COnewbie »

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Re: MyECU current draw when switch is off.
Reply #3 - 07/25/11 at 07:47:56

Is it the MkIV or the MkIII

Do you get the fuel pump cycle when you turn the key on?

There are two places where the 12V can enter the ECU.

First there is pin 26. This is the keyed +12V and should therefore by at 0V when the key is off.
This input switches a transistor that pulls in the ECU relay.

The output of the transistor is pin 4. This should be at 12V. It is pulled to 0v to energise the relay.

The main feed is pin 35. This should be at 0V when the relay is not energised.

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COnewbie Full Member Offline 97 Sport1100i My16M MkVII 2 LC-1s Posts: 120 Central Oregon, USA Gender:	Re: MyECU current draw when switch is off. Reply #4 - 07/25/11 at 07:55:50 Yes, the fuel pump cycles when I turn the key on. I will check pins 26 and 35 and report the results.
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COnewbie Full Member Offline 97 Sport1100i My16M MkVII 2 LC-1s Posts: 120 Central Oregon, USA Gender:	Re: MyECU current draw when switch is off. Reply #5 - 07/25/11 at 08:22:48 Well, no more testing today. When I turn the ignition switch on, the fuel pump murmurs slightly, and the voltage at pins 26 and 35 drops to ~6.5 volts. Looks like I need a new battery in order to check things out properly.
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COnewbie Full Member Offline 97 Sport1100i My16M MkVII 2 LC-1s Posts: 120 Central Oregon, USA Gender:	Re: MyECU current draw when switch is off. Reply #6 - 07/25/11 at 09:29:00 I couldn't resist... I plugged in my Battery Tender and checked that the voltage was 14.4V at the battery. The voltage at pin 4 is 10V with the ignition switch off. Pins 26 and 35 are 0V.
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Re: MyECU current draw when switch is off.
Reply #7 - 07/25/11 at 09:44:09

That all sounds normal.

The fact that your battery is already at 14.4 volts is a concern. What current does you charger pump.
A healthy battery that was discharged should slowly rise in voltage at reasonable currents.

10V at pin 4 sounds interesting. I think relay is about 150 ohm so the 4V across it could explain the current.
The transistor (leftmost FET near L2 on MkIV)shouldn't be drawing any significant current unless it is failing.

If it fails completely then the ECU will be permanently energised ( no fuel prime with key on symptom )
If you did the kit you might want to replace that FET.

Otherwise you should send the ECU back to me for repair. Probably best to wait till your riding season finishes.

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Re: MyECU current draw when switch is off.
Reply #8 - 07/25/11 at 10:25:51

I have a Deltran Battery Tender (p/n 021-0128) which is supposed to be correct for AGM type batteries. It pumps 1.25A Max. I have a YUASA YTX15L-BS battery in the bike at this time. It was supposedly fully charged when I started the testing, so I suspect that since it dropped immediately to 6 volts at the ECU, I am going to have to replace the battery anyway. Although I purchased the ECU, not the kit, from you, I feel competent to replace the FET. I defintely have a MKIV ECU. Which FET are you referring to? There are 3 devices to the left of L2. Do you mean Q6, Q7, or Q3? I don't know where to get an equivalent FET here in Oregon, can you send me a cross-reference or the electrical specs so I can search here?

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Re: MyECU current draw when switch is off.
Reply #9 - 07/25/11 at 11:36:49

Can you send me an email and I'll send you the kit instructions.

A 1A charger is basically going to take 10-20 hours to fully charge. The voltage will gradually increase over that time. The fact that yours has come up so fast really puts suspicion on the battery.

I put lithium batteries in 2 of my 3 bikes including the My Sport 1100. Its never turned over so quickly.

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COnewbie Full Member Offline 97 Sport1100i My16M MkVII 2 LC-1s Posts: 120 Central Oregon, USA Gender:	Re: MyECU current draw when switch is off. Reply #10 - 07/25/11 at 12:16:15 I sent you a PM with my email address. I have been looking at the Shorai Lithium batteries. 186USD is a bit steep compared to 75USD for the YUASA, but it sounds like it's worth it, and Shorai says the Deltran charger is compatible with their batteries. Thanks again for all your help.
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YaBB Administrator YaBB Administrator Offline I love YaBB! Posts: 679 The Land of YaBB	Re: MyECU current draw when switch is off. Reply #11 - 07/25/11 at 15:48:46 Lead acid batteries are really cheap over there. Name brand batteries here are similar to the Lithium price.
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Re: MyECU current draw when switch is off.
Reply #12 - 07/25/11 at 17:29:12

May have nothing to do with the issue but I lost the Odyssey battery charge a couple of weeks ago and it took me two cycles (of recharge) to pin down that I had knocked the LC1 switch to calibration inadvertently. As usual just about to rip everything apart before I clocked the red led and said to myself "what's that all about?" Doh!
Undecided

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COnewbie Full Member Offline 97 Sport1100i My16M MkVII 2 LC-1s Posts: 120 Central Oregon, USA Gender:	Re: MyECU current draw when switch is off. Reply #13 - 07/26/11 at 01:21:54 Good thought, but my Calibration switch box is mounted in the under-seat area right next to the battery, and the lights only came on when the ignition switch was turned on. This morning, I turned the switch on to check, and my battery immediately dropped to 6V. Definitely new battery time.
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97 Sport1100i My16M MkVII
2 LC-1s

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Central Oregon, USA
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Re: MyECU current draw when switch is off.
Reply #14 - 07/27/11 at 09:03:57

I have ordered a new FET, bought a .1uF cap, and ordered a new battery. While waiting for these things to arrive, I decided to check my wiring, just in case. My two LC-1 O2 sensors are being powered from pin 87(NO) of the ECU relay, which also powers the ECU. Is that the correct way to do it, or should I add a separate relay to the relay bank?

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