('98 Rodeo-Battery & Brake Light on > 2400 RPM

My '98 Rodeo has about 65k miles. Recently both the battery and brake lights consistency come on at 2400 rpm. The dealer has checked battery and alternator and both "pass the tests" (but don't know how they tested them). Terminals are clean. Dealer found that the worn rubber on the brake reservoir cap was allowing portion of the cap to touch sensor and believes this is the cause of the problem but can't explain why battery light comes on at the same time as brake light and why this happens above 2400 rpm, but advises that it is safe to drive and just ignore the lights while waiting for the replacement part. However, I find that if I drive with both lights on, after a few minutes the ABS light comes on and sortly after this dashboard fails and car loses power but dropping back down to <2400 rpm seems to solve the problem.

Thoughts or advice? Many thanks.

--Dwight

My '98 Rodeo has about 65k miles. Recently both the battery and brake lights consistency come on at 2400 rpm. The dealer has checked battery and alternator and both "pass the tests" (but don't know how they tested them). Terminals are clean. Dealer found that the worn rubber on the brake reservoir cap was allowing portion of the cap to touch sensor and believes this is the cause of the problem but can't explain why battery light comes on at the same time as brake light and why this happens above 2400 rpm, but advises that it is safe to drive and just ignore the lights while waiting for the replacement part. However, I find that if I drive with both lights on, after a few minutes the ABS light comes on and sortly after this dashboard fails and car loses power but dropping back down to <2400 rpm seems to solve the problem.

Thoughts or advice? Many thanks.

--Dwight
Despite what your dealer says it looks like the alternator regulator is failing. I would say that you at least one of the diodes is bad. One thing you didn't mention during your description of the fault was what voltage does when the warning lights come on. Based on you saying that the ABS light also comes on and you lose power i would think you should also see voltage drop below 12V.

I had similar symptoms in my 96. The fan would kick off as well. Turned out to be the alternator. Beware aftermarket replacements are garbage! I had to do mine twice to get one that worked.

Thanks guys--the dealer just phoned--it was the alternator. Now to try try to get my $ back from the first dealer who told me the alternator checked out fine and just ignore the battery/brake lights (which I did early two Saturday mornings ago at 4:00 AM while on a fishing trip until I lost power and dash dials and indicators).
--Dwight