Unexpected Symptom

[John-D]

This was in a car, not a motor home so technically it does not belong here but since the car, like my motor home, has a chevy engine....

Was going to the store the other day, the road has a slight up-grade and the car downshifted. Never done that before (indicates a loss of power in the engine) scanned the dash including the voltmeter 11.6 Supposed to be 13.6 Did my shopping, headed for the dealer, by the time I got there power was way down, so was voltage (Battery in deep discharge state, actually negative power status, under 10 volts)

Alternator toast

The first symptom was an unexpected downshift.

As it happens, I do know what caused the unexpected downshift. With lower than normal primary voltage the secondary voltage in the ignition (Spark voltage) was also lower, thus the spark was weaker and less power was produced, also, the computer, at some point, goes to default and no longer optimizes the engine, result, still less power.

This post is provided as a help, should you see an unexpected downshift. I get my car back Monday, New HD alternator, plus install, $400 (roughly)

[John-D]

This was in a car, not a motor home so technically it does not belong here but since the car, like my motor home, has a chevy engine....

Was going to the store the other day, the road has a slight up-grade and the car downshifted. Never done that before (indicates a loss of power in the engine) scanned the dash including the voltmeter 11.6 Supposed to be 13.6 Did my shopping, headed for the dealer, by the time I got there power was way down, so was voltage (Battery in deep discharge state, actually negative power status, under 10 volts)

Alternator toast

The first symptom was an unexpected downshift.

As it happens, I do know what caused the unexpected downshift. With lower than normal primary voltage the secondary voltage in the ignition (Spark voltage) was also lower, thus the spark was weaker and less power was produced, also, the computer, at some point, goes to default and no longer optimizes the engine, result, still less power.

This post is provided as a help, should you see an unexpected downshift. I get my car back Monday, New HD alternator, plus install, $400 (roughly)

[DriVer]

The 2 properties that are in common in any vehicle that requires 12 volt power is to be certain that adequate voltage is provided to all the vehicle's systems and that an secure ground exists.

[John-D]

I agree DriVer, but I just thought it was unusuall that the FIRST symptom I noticed was a loss of power.

I do undrestand how it works, (In fact I posted that) but the reason for posting is to let folks know that if things seem weird, check the voltage

In a motor home if I lost the alternator I'd not have a problem... I push a button and about a minute later (or less) I've gut full power back courtesy of Mr. Onan and Mr PD-9180