Topic: HELP! 12v+ at the battery, 10.5v everywhere else!

[yodagruv]

I need the benefit of this forum's expertise and experience.  My '75 CB550K has a good (new) battery offering 12v+ to the electrical system and the alternator is providing more just as it should, however all other places in the electrical system show 10.5v.  It seems that is enough to dimly operate signal markers and moderately operate the headlight but my flashers and horn are inoperable due to this and i suspect the coils are suffering as well.

We jumped a hot lead straight off the positive battery terminal to both the horn and flashers and they function properly under those circumstances, but that's obviously not a feasible solution, so what do you guys think is up?  Voltage Regulator? Rectifier? Something else?

HELP!

[Alan F.]

You may need to clean the connection from the negative battery terminal and the frame, but the simple solution may be adjusting your voltage regulator.  There is a proceedure in the manual.

[yodagruv]

which manual?

[scottly]

Check the fuse holders. Make sure the clips are clean and are gripping the fuses tightly.

[DH]

If all else checks ok like mentioned, check voltage going to and after the ignition switch.

[yodagruv]

You may need to clean the connection from the negative battery terminal and the frame

That's fine, cable looks recent, too.

Check the fuse holders. Make sure the clips are clean and are gripping the fuses tightly.

Fuses and clips are good to go.

make sure there's 12v at the main fuse itself

Is that the 15A fuse on the far right?  The other two are 5A and 7.5A i believe.

May be voltage drop thru the ignition switch.

How would i tell?  We tested for continuity in the ignition switch and it was fine in that regard.  How can i check voltage there?

...the simple solution may be adjusting your voltage regulator.  There is a proceedure in the manual.

i didn't realize you could adjust that, i don't see anything in the owners manual or in the common service manual about adjusting a voltage regulator.

[scottly]

...the simple solution may be adjusting your voltage regulator.  There is a proceedure in the manual.

i didn't realize you could adjust that, i don't see anything in the owners manual or in the common service manual about adjusting a voltage regulator.


[/quote]
Don't adjust the regulator to compensate for a voltage drop in your wiring.

[yodagruv]

Don't adjust the regulator to compensate for a voltage drop in your wiring.

Then how do you correct it?  i would think that's what the regulator would do.  12V in should be 12V out, right?  What am i missing?  Does everything go through the ignition switch first?

[scottly]

 What am i missing?  Does everything go through the ignition switch first?

Yes. Also, any connectors along the way may cause a voltage drop if dirty or corroded.

[IndyFour]

Dirty contacts in the switches (ignition switch, light switches, horn button, etc.) will cause a current drop.  If you can determine where the current drops closest to the battery, then you will likely have the culprit....but then again, it might just be several dirty terminals and switches that are adding up to increased resistance and low voltage at the point of load (i.e. lights, horn, etc.)  If all of the hot leads inside the headlight bucket show low voltage, then I'm betting that it's a bad connection or the ignition switch.  If the leads coming off of the ignition switch (key) are normal voltage, then it's probably dirty switches for the lights, horn, etc.  You have to remove the switch assemblies from the bars and give them a good cleaning and a fresh coat of electric grease.

I had a voltage drop in my headlights resulting in a dim beam.  My solution was to install a relay for both the low and high beams and ran a dedicated hot to the battery with a new fuse.  Lights are now brighter than they probably were new.

I would start by looking in the headlight bucket for loose connections or corrosion and test at various points if you haven't done that yet.

Good luck.

[yodagruv]

Hey, guys i really appreciate all the input so quickly!

We did open up the handle bar controls and clean them, so that's covered.

Every single connection we expected to have 12V on only had 10.5V consistently, no variation except may a couple of hundredths; for instance, Ignition coils, horn, blinkers, all lights, really.  Bought a new winker, just for kicks.

Had the headlight out of the bowl and all the connections we inspected there and, in fact, all over the bike are just peachy, no corrosion, etc. If there's a bad connection it's very, very early in the system.

Which makes me think if the key switch precedes all other connections that may be the most likely and least expensive culprit.  How can i test voltage in and out of it, though, the connectors are all closed off inside the connector.  Bridge them or something?

[DH]

Ignition switch has a 4 wire connector that plugs to another connector half in the main wiring harness. Usually located under the tank. separate the two connector halves and check for corrosion inside. Clean/repair if nec. If ok, jumper the black wire to the red wire, and the brown wire to the brown and white wiire. By doing this, you are bypassing the ignition switch.If that fixes it, get a new ignition switch. Otherwise, refer to other previous suggestions.

[yodagruv]

Perfect.  That should make an "X" across the connector, correct?  If that is not a fix, then check the regulator?

[scottly]

make sure there's 12v at the main fuse itself

Is that the 15A fuse on the far right?  The other two are 5A and 7.5A i believe.

What voltage do you measure at each end of the 15A fuse. (it feeds the ignition switch)

[yodagruv]

What voltage do you measure at each end of the 15A fuse. (it feeds the ignition switch)

Not sure.  Will check again, may be next weekend, though, my father in law is the electrical dude, my meter sucks.  I could do the jumper biz, though, Monday or Tuesday.

[DH]

Perfect.  That should make an "X" across the connector, correct?  If that is not a fix, then check the regulator?

Yes I believe so. If that doesn't fix things, the problem is elsewhere.
As mentioned earlier tho, regulator adjustment is only done when the charging system is not operating properly. Post your results.
If the ign switch is ok, someone with more electrical experience may have something more to add. And re read the previous posts too.
They're good ones.

[yodagruv]

got it.

[scottly]

If you get good readings at the fuse, try unplugging/replugging the ignition switch a few times; may be corrosion on the connectors inside the plug.

[yodagruv]

They were clean.

[scottly]

What voltage do you read at the fuse?

[yodagruv]

What voltage do you measure at each end of the 15A fuse. (it feeds the ignition switch)

Not sure.  Will check again, may be next weekend, though, my father in law is the electrical dude, my meter sucks.  I could do the jumper biz, though, Monday or Tuesday.

[scottly]

If it were me, I would do the simple voltage measurement, before trying to jumper switches. If the fuse has good voltage in and out, then move on to the ignition switch. Being aware that over 90% of electrical problems occur in connectors, I would first suspect the very plug you are talking about jumping. 

[yodagruv]

Yeah, i'll check the voltage at the fuse first. The connectors we inspected, including the key switch, were all clean and good to go.

[scottly]

Keep us posted!

[yodagruv]

right on.