What would you check to fix a P1633 code on a 1999 Ford F-150?

Answer 1

These are a few things I found regarding your code; P1633 Keep Alive Power Voltage Too Low (Ford) ------------------------------------------------------------- You need to check connections at the battery and or computer to get rid of the code that you are getting. ----------------------------------------------------------- Various Electronic and Drivability Symptoms and Codes:

2005 F-Super Duty trucks built before 5-11-05 may exhibit various electronic-related symptoms due to loose/miss-installed fuses in the engine compartment fuse box. These symptoms may be intermittent. The fuses should be inspected to verify they are installed into the terminals in the fuse box and not along side the terminals.

Fuses--Symptoms #10, 10 amps: Check Engine Light; Codes P1633, P0446

Answer 2

Check the battery:

P1633 Keep Alive Power Voltage Too Low (Ford)

It means that at sometime in the past the battery voltage was below specs at the PCM and set the code.The battery provides 12 volts to power everything,the car probably sat for a while and probably took a long time to start or had to be jumped off to start.... when the voltage got below 9 volts it set the code.

The code is more of a indicator for us more than anything.. the computer learns as you drive and all the code is saying is that it lost it's power to itself and can loose that learned information.

Have a shop inspect the battery for being weak or dying as well as your battery connections.. if all is fine, I wouldn't worry as my guess is the car's code was set cause it sat unused for a while