Author Topic: 2002 California EV Tachometer is Dead (Read 15718 times)

Brooksr13 · « **on:** March 18, 2015, 05:11:54 PM »

OK, So now in my continuing saga of silly events, I agreed to look at my cousins wife's 2002 California. She needed a new battery, new tires and had several oil leaks. Not being able to start it, I went and picked it up on my trailer and brought it home. First Mistake.

I then fixed all that was wrong with it and found several electrical issues that she had not known about. Burned out TS relay..etc.

Once I had it all ready to go, it of course fell off of my lift, bending the bars and breaking a mirror and clutch lever. Long story short......On the test ride after replacing all the bent parts I noticed that the Tach was not responding. I checked the wiring and all looks good, I took out the tach and connected it to my Centauro and it revs fine.

I'm kind of at a loss here. I have looked at the wiring diagram and it looks to me like if one of the wires were bad, several other things should be showing signs of not working.

Any ideas??

Mark

normzone · « **Reply #1 on:** March 18, 2015, 05:16:51 PM »

No, but congratulations on having a cousin who's wife has a Guzzi.

Brooksr13 · « **Reply #2 on:** March 18, 2015, 05:23:16 PM »

Yes that is unusual, he rides a Honda.

oldbike54 · « **Reply #3 on:** March 18, 2015, 05:28:14 PM »

Hmm , did any tachs of that era ever work for more than a month ? :o :D

Dusty

normzone · « **Reply #4 on:** March 18, 2015, 05:37:14 PM »

Given the behavior of my instruments I agree, but in this case he's got a proven tach, it's just on the wrong bike.

oldbike54 · « **Reply #5 on:** March 18, 2015, 05:43:55 PM »

Quote from: normzone on March 18, 2015, 05:37:14 PM

Given the behavior of my instruments I agree, but in this case he's got a proven tach, it's just on the wrong bike.

It's FM ;D Dunno . Bad ground seems to be a popular answer .

Dusty

Brooksr13 · « **Reply #6 on:** March 18, 2015, 05:46:05 PM »

Well the Centauro Tach does not work on the California and the California tach works on the Centy so that seems to say that the Tach itself is ok.

Mike Tashjian · « **Reply #7 on:** March 18, 2015, 05:49:31 PM »

On my Stone the the instrument light bulb on the tach is yellow and the ground is black. The tach wire power positive is fed from the neutral/other bulbs/ lights and the negative wire is yellow/black going to the ECU. Mike

Joliet Jim · « **Reply #8 on:** March 18, 2015, 06:31:14 PM »

If the starter button sticks in my centauro tach will not work.

Brooksr13 · « **Reply #9 on:** March 18, 2015, 07:15:22 PM »

None of the wiring was changed when this occurred so i am pretty sure that isn't the issue. also the starter button is not stuck and returns when pressed.

Mark

oldbike54 · « **Reply #10 on:** March 18, 2015, 07:19:55 PM »

Quote from: Brooksr13 on March 18, 2015, 07:15:22 PM

None of the wiring was changed when this occurred so i am pretty sure that isn't the issue. also the starter button is not stuck and returns when pressed.

Mark

May have missed it , was the tach working on the EV before the tip over ?

Dusty

Brooksr13 · « **Reply #11 on:** March 18, 2015, 07:29:04 PM »

Unknown, so i kind of feel responsible for it. I'm thinking that the Tach is good since it runs fine on my Centauro. Just not sure where to start looking electrically on the California.

Mark

Mike Tashjian · « **Reply #12 on:** March 19, 2015, 08:53:17 AM »

The two bulb wires do not run the tach so, check the negative wire(yellow/black) back to the ECU. Then check the positive wire for power. Compare what you have from your other bike that works. I would guess either no power (first), or no signal from the ECU probably not(but the wire could be damaged)since the bike runs. Mike

StuCorpe · « **Reply #13 on:** March 19, 2015, 09:04:54 AM »

I believe the yellow wire is strictly for the light bulb, black wirer is ground for light bulb and could also be ground for the tach. There is another wire (not sure of color) that goes back to the ECU (computer) which is the wire that drives the tach.

Kiwi_Roy · « **Reply #14 on:** March 19, 2015, 09:50:36 AM »

You should have + - and a wire from the ECU (actually from somewhere else if it has the large P8 ECU)
I think it's a yellow wire with black stripe, it might be run outside the loom. You could probably run a new wire
to a coil terminal if you can't locate it.
I believe the Tach gets 12Volts from the headlight relay, is the light going?

Brooksr13 · « **Reply #15 on:** March 19, 2015, 11:02:38 AM »

Both the Tach light and headlight are fine.

Yellow Wire goes to Tach Bulb

3 other wires are :

Yellow/Black -------> ECU
Black --------> Ground
Red/Green --------> looks to power all indicator bulbs and terminates at the Starter relay and start switch

Mike Tashjian · « **Reply #16 on:** March 19, 2015, 02:19:36 PM »

There is a mention of a Black wire with a ringed connector for another ground wire to the body of the tach on my Stone. I believe it goes on one of the rear studs. It was taped on bikes like my Stone that did not come originally with a tach. It was mentioned in the tach installation instructions. Could you be missing that second ground? I just don't remember that far back. Mike

Kiwi_Roy · « **Reply #17 on:** March 19, 2015, 02:49:13 PM »

As mike says, there is a ground for the light and a Negative for the electronics, this is shown in the manual.

Brooksr13 · « **Reply #18 on:** March 19, 2015, 02:55:33 PM »

Yes I have both grounds and they are good, I have power to the tach on the Red/Green wire.
If the Tach gets its signal from the ECU shouldn't I read voltage on the Black/Yellow wire???

Mark

Brooksr13 · « **Reply #19 on:** March 19, 2015, 03:13:39 PM »

OK Here is what and how I have tested so far:

Both Grounds on the Tach show continuity between the connector on the Tach and the fin on the Voltage Regulator

When the Key is turned on, I read power on the Red/Green wire and the Tach light bulb lights up.

I unplugged the ECU, found the Yellow/Black wire in the plug and tested continuity between it and the Yellow/Black connector on the Tach harness.

What am I missing here???

Mark

Brooksr13 · « **Reply #20 on:** March 19, 2015, 04:25:12 PM »

And just to make sure I was not crazy, I took the tach out of the California and put it on my Centauro and it works just fine.

So the tach is fine......

Kiwi_Roy · « **Reply #21 on:** March 19, 2015, 06:03:15 PM »

Forget about the lamp supply, it is separate
The tach should have
Black wire on a negative terminal (not the one on the case, that's for the light)
A red/black wire +12 Volts from the headlight relay on a Positive terminal
Yellow/black pulses from the ECU on another terminal,

Which ECU do you have, the large P8 or smaller 15M

If you turn the key on and scratch a wire from the pulse input terminal onto + you should be able to get it to go upscale a little bit.

It's always possible the ECU pulse outputs fried.

Mike Tashjian · « **Reply #22 on:** March 19, 2015, 07:08:29 PM »

I think you have the 15M ECU. I do not know how to check the tach signal. But so far you seem to pointing towards the ECU being the problem. Mike

Brooksr13 · « **Reply #23 on:** March 19, 2015, 08:02:13 PM »

Yeah, I'm coming to that conclusion. Before I started working on this bike, she had a completely dead battery and I know that she tried a number of times to jump start it using a car battery. Could that have blown the ECU?

Mark

LaMojo · « **Reply #24 on:** March 19, 2015, 08:16:12 PM »

Find someone that has an oscilloscope that will do a signal trace for you. Maybe someone one at the local trades school?

rodekyll · « **Reply #25 on:** March 19, 2015, 10:58:45 PM »

It's dead, Jim. :'(

Too soon?

I'm going with either the signal wire (which I thought was gray . . . where did I come up with that?) or the ecu signal. Is it getting a pulse generated by the ecu or does the ecu simply pass on the cam position sensor signal and the tach does x2?

Brooksr13 · « **Reply #26 on:** March 19, 2015, 11:26:07 PM »

Signal Wire: Yellow/Black is good end to end...Just don't know if the ECU is producing a signal. Found many weird things electrically that were bad on the bike and wondering if trying to jump start a dead battery can cause damage to the electrical components. I could barely get the old battery out of the bike as the sides were swollen. I think she dodged a bullet as it didn't just burst on her.

Mark

Kiwi_Roy · « **Reply #27 on:** March 20, 2015, 07:32:17 AM »

I think the 15M ECU must generate a nice square pulse for the tach, My 78 with the P8 gets a pulse from elsewhere.

Do you have another bike you can try the ECU in, see if the tach works in it?

You say in your first post the bike is running so I doubt the ECU was damaged by jump starting, they have a safety diode that protects it from reverse voltage.

If it turns out the ECU output is not pulsing I would be tempted to try picking up a pulse from one coil

Chuck in Indiana · « **Reply #28 on:** March 20, 2015, 08:18:03 AM »

Quote from: Kiwi_Roy on March 20, 2015, 07:32:17 AM

I think the 15M ECU must generate a nice square pulse for the tach, My 78 with the P8 gets a pulse from elsewhere.

Do you have another bike you can try the ECU in, see if the tach works in it?

You say in your first post the bike is running so I doubt the ECU was damaged by jump starting, they have a safety diode that protects it from reverse voltage.

If it turns out the ECU output is not pulsing I would be tempted to try picking up a pulse from one coil

Me, too..

Brooksr13 · « **Reply #29 on:** March 20, 2015, 01:28:54 PM »

Can you explain, "Pick up the pulse from one coil" ?

Mark

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Author Topic: 2002 California EV Tachometer is Dead (Read 15718 times)

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