That Blankety-ty blank batttery light

[MasterGuns]

OK, I have read a few threads here about that doggone battery light that wont go off. I have one. and have followed the recommended fixes to the tee. Even purchased the 2.2 and 1k resistors and tried fooling the light to go off. No deal. I am just about to resort to the duct tape fix like some have recommend but thought I give it one last shot by soliciting guidance here.

 

The battery is good and tests at 12.45 volts even after sitting for some time. But just to be sure while trying to diagnose this thing tonight I had a battery tender on it and it had gone up to 12.55. Anyway, it does have a battery sensor attached between cells 3 and 4. There is a resistor in-line just after the sensor. Voltage just after the sensor is 6.24 volts. Voltage at the plug is 6.24v where it connects into the white with red stripe wire. I had even followed the white/red wire to the connector on the back of the CMS at the rear of the instrument panel - voltage 6.24v. Therefore, I thought the CMS had gone bad. I had a replacement and tonight I swapped them out. Result - Battery Light still flashing. What the heck! Any ideas here from those that perhaps have been confronted with this problem. I am all ears or in this case; eyes.

 

[ctraylor]

This light will come on if the cell it is in is low on water. Make sure the cell is full. I replaced my battery with a gel battery and just attached the wire to the hot post and the light has not yet come on. I didn't install any resistor there was already one in the line.

[lonestarmedic]

Herb- Make sure to remove the sensor. Then install the resistor in its place. Finally, run the free end of the resistor to a switched positive power source. Some folks splice into the accessory terminal at the top of the fuse panel. I make a little assembled lead when doing this. I solder wire on either end of the resistor. Then a bullet connecctor to fit the factory sensor plug. I put the resistor in heat shrink tubing and lay an old piece of nylon zip tie along side it to support the resistor leads. Kinda like a splint. Then I shrink the tubing over the resistor and tie. Put a ring terminal on the other end to fit the accessory screw.

 

JB

[bongobobny]

Unplug the CMS and see if thazt 6.24 volts is still there, betcha it won't be!! I'm, thinking that the voltage you are seeing is coming from the CMS but I could be wrong. I/'m thinking that may be a threshold voltage that has to see more than that level to cancel??

 

Try cleaning the probe. It may be gooked up and never senses the battery acid abd in turn never sees the voltage level

[MasterGuns]

I have even tried connecting the Battery Light circuit direct to the battery and providing it the full 12 volts. Still on. And yes the 6.24 volts is making it all the way to the CMS. That is why I thought the CMS was bad are replaced it. Still on whether it is getting 6.24 volts (which is what the resistor allows through) or 12 volts. I simply don't understand. Perhaps there is more to it that just providing voltage to the CMS. Can someone check the amount of voltage being sent to their Battery Light circuit. That is the amount of voltage on the light side of the resistor. With a resistor needed in between the battery and the CMS, I am starting to think that even 6.24 is too "much" and confusing this 23 year old.

[Monty]

If you have connected the red/white sensor wire to 12 volts, then you have almost certainly blown the IC chip on the circuit board of the CMS. I have one sitting here that I destroyed following the advice from someone who didn't know what he was talking about.(not from this site).

 

NEVER hook the lead to 12 volts.

[MasterGuns]

If you have connected the red/white sensor wire to 12 volts, then you have almost certainly blown the IC chip on the circuit board of the CMS. I have one sitting here that I destroyed following the advice from someone who didn't know what he was talking about.(not from this site).

 

NEVER hook the lead to 12 volts.

 

This replacement CMS has not been hooked up to 12v just the old one but from what I can tell it never worked anyway. What happens when the IC chip is fried? Does the Battery Light still flash? Whatelse is affected by a fried IC chip? How can one tell if the IC chip is fried; by looking at it? I would be interested since I have the old CMS out and it would be easy to check. What is the ultimate cure for this annoying flashing battery light? Can it be disconnected somehow to deactivate it; otherthan the duct tape thing?

[Monty]

Well, after I tried hooking it to 12 volts, and it didn't work, I had taken it apart to clean up the solder joints and such. When taking it apart, I noticed that the chip had a big hole burned into it...it looked bad. I then read here on the site how the chip can be destroyed by doing what I did. There is also a link somewhere for ordering the replacement chip. I had a spare dash that I had gotten with my bike, and so I just replaced it, and did the resistor mod for the battery. The resistor mod worked great...light hasn't been on since. I DO have the flashing red light, and headlight icon staying on. Some here say that's because I have an LED license plate frame tail/stop light added to my bike. I haven't unhooked it and verified that yet, but I would think that would make the tail light icon come on, instead of the headlight icon. I currently have electrical tape covering the red light.

[Monty]

Here is the quote from mbrood...

 

"The sensor wants to SHOW a voltage to the computer monitor but NOT without resistance. 12V direct will blow a chip in the CMS (it can be relaced but a pain to do it)... The mod is just a 2.2K Ohm, 1/8th watt resistor, in-line from the accessory fuse to the white/red wire connector for the probe... and most auto stores sell the rubber jacketed "Johnson" connector to make up a neat jumper (you need the female).

 

The chip in the CMS is a TD62504P. There are two on the computer board and the battery sensor connects to pin 1 on one of the chips. That is the one to change. "

[Venturous Randy]

I DO have the flashing red light, and headlight icon staying on. Some here say that's because I have an LED license plate frame tail/stop light added to my bike. I haven't unhooked it and verified that yet, but I would think that would make the tail light icon come on, instead of the headlight icon. I currently have electrical tape covering the red light.

When I tow my camper with LED lights, it does not trip any icons on my 83 dash.

I did the battery resistor a while back when I did the Oddesy battery and that has worked perfect.

RandyA

[Rocket]

I DO have the flashing red light, and headlight icon staying on. Some here say that's because I have an LED license plate frame tail/stop light added to my bike. I haven't unhooked it and verified that yet, but I would think that would make the tail light icon come on, instead of the headlight icon. I currently have electrical tape covering the red light.

Did you dis-connect the stock tail light? If so, that could be why it is the headlight icon shown (running lights). I know that the tail light icon shows, if a brake light modulator controls the brake light. As I have this installed on my bike.

[Monty]

Didn't mean to hijack this thread.

 

I have an LED license plate frame that is both taillight and brakelight. I also still have my stock brake/tail light hooked up. The bike had this setup when I bought it, and it works great.

 

The HEADLIGHT icon is the one that's staying on...not the Taillight. The headlight itself is working fine, on both bright and dim. I would imagine that the problem is somewhere in the CMS circuitry, but I could be wrong. When I get time to remove the trunk, and access my rear relay panel, I will disconnect the LED light, and see if the problem goes away...but I bet it won't.

[mbrood]

As I understand it... you have two CMS units and BOTH blink the battery icon... and on one, you KNOW you hooked up the sensor wire direct to 12V... so we can bet that the corresponding IC inside the CMS (TD62504P) is blown and needs replaced... not ridiculous if you have reasonable soldering skills and a good "solder sucker". If not, you can buy the chip and take the unit to a local radio/TV repair shop and they can pop it in for ya.

 

I think you MAY not have any REAL knowledge that the replacement unit didn't already HAVE a blown IC as well. The best test is as earlier stated... hook a 2.2K Ohm resistor to 12V and the other end to the sensor wire at the bullet connector... then turn your ignition on... if the light blinks, the IC is probably fried.

[bongobobny]

As far as the headlight indicator, what we are TRYING to tell you is 6that both taillights have to be connected AND working for the circuit to work right. It is a curent sensing line and needs to be drawing the right amount of current to work.

 

What I meant by your 6.24 volts you were reading is that it may have been COMING from the CMS and I wanted you to disconnect the CMS and see if the voltage was still on the line when NOT connected to the CMS...

[Monty]

Both of my lights are hooked up...stock and LED.

What I am trying to tell you, is that the headlight indicator has NOTHING to do with the taillights. There is a separate taillight indicator for that.

[Neil86]

Monty....

are you sure that both headlight beams are okay and the Reserve Lighting Unit isn't kicking in when you switch to the failed filament? Is the "headlight" (the white light) on dash dimly lit to indicate its functional?

The RLU sends power to the functioning filament to prevent losing your headlight when you switch to a failed filament....but normally the Headlight light will be bright...if its working, when you switch to the failed beam.

Edited May 9, 2009 by Neil86

[bongobobny]

Both of my lights are hooked up...stock and LED.

What I am trying to tell you, is that the headlight indicator has NOTHING to do with the taillights. There is a separate taillight indicator for that.

 

You are correct, and I was TERRIBLY rude to you, and I publicly apologise! I got a little confused with who posted what and who was having what problem.

 

My point was that for both the headlight and the tail light indicators, the circuit works the same way. They are current sensing circuits and monitor the amount of current that the bulbs are drawing. This is done via a shunt resistor which develops a voltage proportional to he curent being drawn. the more the current draw, the more voltage developed across this shunt, the happier the differential comparater is .

just like the battery acid circuit, as long as the input voltage is greater than on the other side of the comparater the light and indicator stays off less voltage and the circuit trips and sends the signal to the appropriate indicator and also supplies pulsing voltage for the red light. In the case of the taillights, if one bulb is out, it draws half the current, so the circuit sees only half the voltage, and trips the indicator.

 

OK enough of the technical stuff. Here's what the problem(s) could be. If you have some corrosion or dirt on the connector, you will loose a smal amount of voltage across it, and the light will still light but not draw as much current, triggering the indicator. Also, if the bvulb isn't the same type as the original, it may draw less current and trigger the indicator. Drawing more curent than the original, or adding extra bulbs, does nothing as with more bulbs or heavier draw, MORE voltage across the shunt, no indicator.

 

I suppose there is also a possibility that the reserve lighting module is also messing up things!

 

Once again Monty, sorry for being so rude last night, I was way out of line!

[Monty]

Don't worry about it Bob. I am easy to get along with.

 

All I know is, my headlight works, and then when I switch to high beam, it gets alot brighter, so I am assuming both filaments work. I haven't actually tried blinding myself by looking into the light itself to see. I actually see quite a difference between the two. The white indicator on the dash has never been on. I have already soldered the CMS. I may try to pull it again, and clean up the connectors on the main plug.

[lonestarmedic]

Herb-if the chips are blown, send it down to me and I can replace them. Not too bad of a job. I have a good solder station with a big magnifier light. (Fixes that mature eye problem!)

 

JB

[MasterGuns]

Herb-if the chips are blown, send it down to me and I can replace them. Not too bad of a job. I have a good solder station with a big magnifier light. (Fixes that mature eye problem!)

 

JB

 

jb, are you saying that you also have the chip? I would love to send at least the CMS I have out. If you don't have that particular chip, where can a fellow find one? I called Radio Shack as recommended by someone here and they was no help at all. No help with the cb knob either. Come back!!

[RossKean]

I don't know if this may be part of the issue or not...

It was mentioned in the original post that the battery voltage was 12.55 after being on a battery tender. A FULLY charged lead-acid battery should be 13.0 V (resting), or a little higher if just off the charger. Maybe the battery has a bad/weak cell? I admit that I know nothing about the sensing circuit or how it works.

 

Ross

[timgray]

..... This is done via a shunt resistor which develops a voltage proportional to the current being drawn. the more the current draw, the more voltage developed across this shunt, the happier the differential comparator is....

 

 

Actually in my 83 it's not like that at all. The Computer simply runs the power for the headlight through a coil wrapped around a reed switch. Current flow will close the reed switch because of the magnetic field. It looked to be the same for the brake light sensor as well. They may have upgraded to shunts and comparators for newer bikes though and I believe that is what they did for the Battery indicator. The kickstand, oil and brake senders are simply looking for ground. I have not been inside a 84+ computer to see if they upgraded things.