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1990 XR250 wiring woes

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Hi all.

I've got a 1990 XR250R, and I've got some serious wiring troubles.

None of my lights work. None at all. The bike starts and runs just fine, but nothing else.

 

I've got a Haynes manual, and while in the wiring diagrams it says there are grounds, it doesn't say the actual physical location (as far as I can tell).

Where are the grounds on the bike? 

 

Secondly, does anyone have resistance values for the regulator/rectifier? My brother has a XR600 and the resistances seem close, but I'm not sure what spec is. And I can't swap them over to test because the plug is different.

 

Other than that it's a fantastic bike!

 

Thanks

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You probably don't have a rectifier. Just a regulator.

The ICM has its own power coil on the stator assembly so it will still run fine if the regulator or lighting coil is not working properly.

Have you checked for voltage coming straight from the lighting coil before the regulator? Pink wire and yellow wire. Make sure you've set your multimeter to A/C voltage.

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You probably don't have a rectifier. Just a regulator.

The ICM has its own power coil on the stator assembly so it will still run fine if the regulator or lighting coil is not working properly.

Have you checked for voltage coming straight from the lighting coil before the regulator? Pink wire and yellow wire. Make sure you've set your multimeter to A/C voltage.

I have not. Just bridge the pink and yellow? Is the lighting coil a common thing?

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You can narrow down the issues and see if the easy to check and common failures are covered.

Is the bulb OK?

Does the tail light work?

 

I don't have a 90 XR250R wiring diagram but that was about the time Honda started started switching from internally grounded stators for lighting to floating ground.  The clue is the number of wires coming out of the alternator and the number of wires connecting to the regulator. 

Internally grounded have two wires out of the alternator, the blue is the lighting power, and only two wires at the regulator.

Floating ground have 3 wires out of the alternator, the pink and yellow is lighting power, and four wires at the regulator.

 

The only check you can do on the regulator with a multimeter is check for very high resistance from the inputs to ground.  Yellow and pink, each  to green.  The regulator is a shunt; it puts a load on the stator to control the voltage via a short to ground. there should be no short to ground from the multimeter voltage.

A quick check of the alternator is disconnect the alternator wire(s) from the regulator, set the multimeter on AC, and check the voltage while kicking, any voltage is good, at idle the voltage should be over 30. Test between the pink and yellow, or the white/yellow and ground. 

You can also quickly check the stator winding by checking the resistance between the pink and yellow, and each to ground. Or the blue to ground on the internally grounded. I don't have a manual handy to post up  the resistance.

 

Here is a 96-04 wiring diagram, most colors except as noted above will be the same as the 90.

The chassis ground point should be near the coil or on the left side just aft of the steering head, you'll need to pull the tank.

White/yellow from the regulator goes into the wiring harness and becomes blue for the head light and tail light.

Early, and even into the 90s, XRs used a brown wire to power the tail light.

The double female bullet connector behind the number plate is the ground connector for the headlight and the kill button.

 

 

99_XR250R_Wiring_Diagram.gif

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Wow, awesome post. I just got back from being away, so I'll give all of that a try now.

Cheers

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Just checked the pink to green and yellow to green for wires coming out of the regulator. It bounced around between 6-12 mega ohms for both of them. Is that correct? Or have I got it wrong

 

-edit-

Fixed! I think.

Fiddled around with the green wire connection near the reg and the seemingly perfect connector was not perfect.

Redone with spades and taped and it's all good

Edited by econti

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