Battery warning indication

[lvsloan1]

I had to replace my CMS on my 1990 RSV trike as the original quit showing anything. I bought a used unit off of Ebay & everything was fine until about 2 days later. The red warning light started staying on with the battery emblem in the CMU showing but I've always had a maintenance free battery on it ever since we've had the trike & the wire has always been hooked to the accessory 12v side. With the key on, I checked the voltage at the electrical connector going into the rear of the cms on the white w/ red stripe wire, & it shows 12v. I hooked up a 2.2 - 1/4 watt resistor in this wire & the voltage going into the CMS now shows about 3v but the warning light & the battery emblem still shows. Is there a way to disconnect this circuit from the digital info readout & the red light? I want the warning light to work on fuel gauge & everything else but don't want to see the red light on all the time because of the battery low indicator. Guess the used CMS I installed went bad on this part of it's circuit?:gah:

 

[bongobobny]

The CMU needs about 5 volts logic level to work properly. The standard mod for this is to use a 1K to 2K ohm resistor to the plus side of the battery. NEVER connect the lead directly to the battery plus, the 12 volt signal blows up the logic chip! Sooo, try a 1K ohm resistor and see of that brings your level closer to 5 volts. A little higher is OK, it just does not like "rail" (supply) voltage for a logic input...

 

[lvsloan1]

Thanks Bongobobny, but I've already tried 1k & a 2k resistor but w/ no luck. So I just soldered the 2k resistor in line w/ a new wire from the acc + to the CMU so if I ever get the money to buy another CMU I have everything already to install it. Thanks again for ALL your help & have a great day!