KLM wrote on 11/03/25 at 12:54:09:
Not paying cliose enough attention and hooked my new lithium battery up backwards.
Just a multimeter for testing
I don't think that a multimeter will get one very far towards differentiating a functional ICU from a non-functional one, at least, not without a published procedure from the manufacturer.
Generally, ICUs are pretty "hardened" against the usual mistakes, like a reverse voltage cranking battery, and also reasonable levels of overvoltage. What IS vulnerable, is the rectifier, whose diodes treat the reverse voltage like a short, and quickly blow. Also, of course, fuses, and possibly sections of harness that might be fusible links. Not sure if there were any of these in the Savage, but the use of fusible links was a more popular practice back in the 80s.
If you haven't already, I would check all the supply side and ground wiring that serves the ignition system, and also disconnect the Rectifier / Regulator, and see if the bike will start and run without that component attached. Also, be aware that ICU's generally have pre-set internal voltage limits, that will prevent them from attempting to make spark if supply voltage drops too low, generally around 10VDC. You need a good battery. I use a big car battery as a temporary power source when diagnosing and testing.
The thread I linked to in my previous post, identifies certain diodes on the ICU board, which are there to protect from high voltage transients. If the ICU is nonfunctional, a visual inspection might reveal some burnt components, which can be replaced. I'd also be alert for failed capacitors, electrolytics can age out. These might require desoldering in order to test them however. A lot of specialized knowledge / experience is valuable in diagnosing electrical problems, and it's something of a lost art vs. a few decades ago.
There does exist a few service providers that MAY offer repair:
https://www.regulatorrectifier.com/products/atv-and-motorcycle-cdi-tci-ecu-ig...https://ecumeistro.com/motorcycle-ecu/https://www.cdielectronics.com/premier-repair-service/