25hp CDI bad? Help troubleshoot

[Mozella15]

Just to be certain, you did exactly what is in the service instructions I posted? Engine RPM at least 2000 and grounded the" wire harness side."
I have to ask because it is another common theme here to give people instructions, they come back and say they didn't work, only to find out later that the instructions were not followed correctly.

I am sure others have put a tach on a small engine and wanted these lights to work. I remember a guy on here rigging out a LED light up on his dash for oil pressure. He had the same trouble as you I think, it would not light a incandescent bulb...I think.

The regulars on here are doubtful about CDI and ECU failures because they rarely fail. Many people end up with spare ones in the end.

Yep........ 2500 rpm and I grounded the wire harness side for more than 10 seconds; at least 30 seconds really.

I hear what you're saying about CDI's being reliable. But I'm reminded of an early Yamaha 15hp four stroke I owned which drove me crazy until I replaced the faulty CDI. I too guessed that it was very doubtful that a brand new CDI would work for a little while and then suddenly fail. And, as you know, troubleshooting a bad CDI is not necessarily easy. It happened in Georgetown, Bahamas which made the repair much more challenging. Customs is NOT your friend in the Bahamas and communications were were pretty sketchy.

Anyhow, if I could get the factory LED lights to work but the tach bulbs would NOT illuminate, then I would probably live with it. But the fact that the LED's test OK yet they don't function properly makes me want to fix the problem because I don't like buzzing around without any low oil pressure or overheat warning protection.

Again, I want to make it clear that I'm not attempting to drive a 12 volt incandescent bulb with voltage down around one and a half which would be appropriate for an LED. All I'm looking for is a ground which as far as I can tell the CDI is not furnishing to the LED's; therefore, I would not expect the tach mounted bulbs to illuminate either.

[99yam40]

the LEDs are just one way the motor tells you it has a problem,
it should also limits RPM

How does the CDI know the oil or overheat signal is given if all those switches do is provide a ground for the lights?
if it measures the current flow to the lights, then if the LEDs do not work, would the CDI still know there was a problem?

another question, if a LED fails, does it fail shorted or open?

[Mozella15]

the LEDs are just one way the motor tells you it has a problem,
it should also limits RPM

How does the CDI know the oil or overheat signal is given if all those switches do is provide a ground for the lights?
if it measures the current flow to the lights, then if the LEDs do not work, would the CDI still know there was a problem?

another question, if a LED fails, does it fail shorted or open?

The overheat and low oil pressure sensors aren't connected to the LED's. They're connected to the CDI. I don't think anyone is claiming that the CDI measures current flow to the lights or the LED's, are they?

[99yam40]

The overheat and low oil pressure sensors aren't connected to the LED's. They're connected to the CDI. I don't think anyone is claiming that the CDI measures current flow to the lights or the LED's, are they?

well every one said to ground the oil or overheat switch to get the LEds to come one.
so do the leads to the switches just go to the CDI and then the CDI sends power and/or a ground to the LEDs.

if the CDI controls the voltage and the ground to the lights and also puts the motor in RPM limit, but these things do not do what they should be doing, maybe the CDI is not getting that signal for some reason.

if someone connected the switches or CDI to a tach that sent 12v to some of the system , could that have damaged the CDI or switches

[Mozella15]

...... snip...........
if someone connected the switches or CDI to a tach that sent 12v to some of the system , could that have damaged the CDI or switches

Perhaps, however, nobody did anything like that.

[99yam40]

Perhaps, however, nobody did anything like that.

your original post kind of sounded like someone did, but I know nothing about this 25

I disconnected the engine mounted warning lights and plugged in the 6y5 83653 Trim/Oil harness which I connected to the tach in accordance to the wiring diagram. Everything works except the oil and water warning lights

[boscoe99]

if someone connected the switches or CDI to a tach that sent 12v to some of the system , could that have damaged the CDI or switches

Or if someone tried to power a 12 volt lamp from the CDI LED warning light circuit I can see that causing harm to the visual warning system. Excessive current flow through the CDI.

Power an LED with 12 volts and watch what happens.

[99yam40]

Or if someone tried to power a 12 volt lamp from the CDI LED warning light circuit I can see that causing harm to the visual warning system. Excessive current flow through the CDI.

Power an LED with 12 volts and watch what happens.

Big question is does the RPM reduction work even if the lights do not

[panasonic]

Big question is does the RPM reduction work even if the lights do not

From what I read he got no lights or RPM reduction...so he has no protection at all.

[panasonic]

Mr Mozella if you replace the CDI and it fixes this problem please report back here as it may help others in the future.

[99yam40]

could there be a problem with a connection or pin in the harness, so the CDI is not seeing the signal

[Mozella15]

Mr Mozella if you replace the CDI and it fixes this problem please report back here as it may help others in the future.

I certainly will. I went ahead and ordered a new CDI. The on-line supplier say, "Usually ships in 3 to 5 days" ;however, when I checked with my local Yamaha dealers, several of them checked the dealer supply chain and all said the same thing: i.e., "Atlanta doesn't have any, L.A. doesn't have any, Chicago doesn't have any. It looks like this CDI is still in Japan and wont' be available until sometime in September".

Note that the I couldn't find any on-line supplier who claimed "......... in stock".

If the Yamaha dealer network has ZERO, what are the chances of an on-line supplier having one? Slim, I would guess but you never know.
So I'll be surprised of my order gets filled any time soon.

[Mozella15]

PROBLEM SOLVED.
I gave this situation more careful thought and re-evaluated my suspicion that the CDI was faulty. In short (no pun intended), I made an error compounded by a booby trap by Yamaha. Here’s the long version:

Even though I had a CDI fail on a Yamaha 15hp in the past, I would have to agree with posters here that they are usually very reliable and my problem is unlikely to be a faulty CDI. Anthough my initial testing pointed to a faulty CDI, I decided to review my test procedure, questioning what I may have done wrong. I decided to start all over again.

In fact, my test procedure was OK, but it turns out my technique was not. I was using a screwdriver to connect the warning signal wires to ground. With a system which gives an instantaneous reaction, this usually works out OK. In other words, if taking a signal wire to ground produces a light or buzzer immediately, no problem. But in this instance, the system reacts with a warning light only after a lengthy delay. Now I’m pretty sure I was not keeping a continuous ground for the entire delay sequence; hence, the test appeared to fail when actually the system was just fine. My intermittent ground was producing a false result.

Yesterday I decided to re-run my tests but this time I made up a proper set of jumper wires so I could ensure a good ground. With the engine mounted LED warning lights connected, grounding the low oil pressure switch signal wire produced a proper light, buzzer, and a reduction in RPM, but only after a significant delay. The overheat warning also produced a positive reaction, but only after a much longer delay. It’s supposed to be 120 seconds. I didn’t time it, but it seemed even longer. In any event, the factory LED’s checked out.

Since they illuminate when the signal wire is taken to ground, I had hope that I could connect my Yamaha analog tach and get a similar reaction since the bulbs in the tach only need a ground to illuminate. The 4-pin connector on the Yamaha Trim/Oil harness physically matches up with the existing connector for the engine mounted LED warning lights even though the wire color codes do not match across the connectors. For reasons only Yamaha might be able to explain, the low oil pressure signal wire to ground matches, but the overheat warning does not. It took a while to confirm this, but I determined that switching the Gray and Green pins on the engine side of the Trim/Oil extension harness would do the job.

Teasing the pins out of the connector was easy using a small jewelers screwdriver. After I swapped the wires around, I re-ran both tests and again after a significant delay, both the low-oil-pressure and high-water-temperature warnings sounded the alarm buzzer and illuminated the appropriate light bulbs in the tach face. SUCCESS. As I suspected, the CDI provides a ground for the warning signal wires after a delay and this ground will illuminate either the engine LED’s or the tach mounted incandescent bulbs IF you connect the wires properly which Yamaha did not make easy for the F25.
Why Yamaha didn’t make the warning system wiring on the F25LA compatible with their factory extension harness is a mystery to me. It certainly would be easy enough to do. Of course, there is no factory literature associated with this little problem. It seems to me that if they offer an engine with remote trim and tilt and console steering, they might anticipate that somebody might someday want to mount one of their factory tachometers at the steering station using Yamaha factory components. Well, it turns out that you can do it, but “plug and play” is not part of the deal.

To be fair, Yamaha claims this scheme will work on F30 to F250 four stroke engines and 40hp to 300 hp oil injected two strokes. No mention of the F25, so I can’t complain too much.

Bottom line for anyone wanting to check their F25 warning system and/or install a remote tach.

1. Be sure to provide a rock-solid grounding jumper wire for the signal wires and wait, wait, wait, for the proper reaction. It seems to take forever, especially for the overheat warning.
2. If you use the 6Y5-83653 Trim/Oil extension harness to connect a Yamaha tach, which is the logical way to do it, oddly you won’t get overheat warning unless you swap the position of the Gray and Green pins at the engine end of the harness.

Thanks to everyone who replied, especially bosco99 and panasonic.

[boscoe99]

Why Yamaha didn’t make the warning system wiring on the F25LA compatible with their factory extension harness is a mystery to me. It certainly would be easy enough to do. Of course, there is no factory literature associated with this little problem. It seems to me that if they offer an engine with remote trim and tilt and console steering, they might anticipate that somebody might someday want to mount one of their factory tachometers at the steering station using Yamaha factory components.

A company cannot be all things to all people. The chances of an F25LA owner wanting to use a multifunction or Pro Series tachometer is about one in a billion. Congratulations. You are the one.

Good news that you solved your problems. Thanks for the feed back.

[Mozella15]

A company cannot be all things to all people. The chances of an F25LA owner wanting to use a multifunction or Pro Series tachometer is about one in a billion. Congratulations. You are the one.

Good news that you solved your problems. Thanks for the feed back.

You may be right; however, when the design engineer was deciding how to wire the F25 warning lights I'm wondering if he said to himself, "Well, I think I'll use the same four pin plug we use on all our other motors; i.e. the one which fits the Trim/Oil extension lead. That will save having to source a new male and a new female connector. But rather than arrange the wires in the plug like I did with ALL other Yamaha engines, I think I'll swap two of them around so that only the low oil pressure warning works normally, but the water over temp warning won't function. That will keep those Americans guessing. I'll never forgive them for that Atomic Bomb thing. Besides, who want's to be all things to all people? The chances of an F25LA owner wanting to use a multifunction or Pro Series tachometer is about one in a billion, which boils down to one guy from Alabama. Screw him and the Atomic Bomb he rode in on."