91 deville going crazy

[brown1911]

Hello everyone, I need some help. My 91 caddy with a 4.9 is acting crazy. It has about 10 codes that keep coming up. When the service engine soon light pops on the car goes into a meltdown, stalling, sputtering, then light will go off and all is well until this happens again. Anybody seen this happen before? I can clear the codes, but when the car throws a fit all the codes come back. Codes are 16, 21, 26, 31, 73, 74, 99 and so on. Please help. Thanks

[maxwedge]

16 is battery overcharge look at the alt output situation first.

[brown1911]

Thanks for the reply Maxwedge. I went out this morning to check charging system. I started the car, ses light was on , car ran real crappy, then all of a sudden light went off, and engine smoothed out. So while I was on my way in the shop to get meter, engine just took off like someone had their foot in the gas pedal to the floor. I had to run I mean run back to the car, and shut off engine. Went got my meter, restarted engine, it ran fine, and system was showing 14.0 to 14.2 volts.