1999 Chevy 1500 LS Battery comes on when humid

Has the check engine light come on at all ?

WHEN YOU SEE BOTH LIGHTS AT THE SAME TIME YOU ARE HAVING BRAKE FAILURE EITHER MASTER CYLINDER FAILING OR ABS BRAKE MODULATOR FAILING.CHECK BRAKE FLUID LEVEL IN BRAKE MASTERCYLINDER. IF BRAKE FLUID LEVEL OKAY. I HAVE SEEN CASES WHERE ALTERNATOR FAILING CAUSING BATTERY VOLTS TO DROP AT 11.8 VOLTS CHECK BATTERY VOLTS AT BATTERY WHILE ENGINE RUNNING SHOULD BE 13.5 TO 14.5 VOLTS AT BATTERY WITH ENGINE RUNNING.IF BATTERY POWER IS OKAY.MORE LIKELY BRAKE MASTERCYLINDER AND ABS MODULATOR COULD BE FAILING. TAKE VECHICLE TO A GARAGE LET THEM CODE SCAN TO SEE WHAT CAUSING ABS AND BRAKE LIGHT TO COME ON.CODE SCANNING WILL SAVE YOU TIME AND MONEY.

turn the key on until dash lights come on but do not start and push the gas pedal too the floor and let up 5 times the oil life monitor should flash and turn key off after that and then proceed as normal. this should reset oil life monitor.

pick up your hood, each headlight has a rod L shaped on the right and left end of the light. they look

like latches. unlatch the rods and pull them straight up. once the rods are removed you can pull out

the headlight assembly and you have access to your running lights. on the battery side, you may have

to remove the battery. good luck!

are your talking about the knock sensor on the lower engine if so and you have water coming out you have a big problem.i think you have the wrong sensor infact i think you have a water sensor.adrian,,,,

On the low pressure side of your system. The high pressure is by the battery on the aluminum tube hooked up to the radiator. Not that one!! But the other aluminum tube hooked up to your firewall going into the cab. Both of em looks alike. Is a quick coupler fitting with a black cap on it.

must have a scanner to reset light but it will come back on until you fix the problem have the system checked to get trouble code that will let you know where to start

Autozone will check the codes for free .Itsounds like a secondary ignition problem possible plug wires :)

before you drop tank again, check fuses & relay.then disconnect fuel line @ filter turn key to on position should hear fuel pump run and get gas stream out of line. if no flow from line new pump faulty be sure & remove negative battery cable first good luck.

I would check belt to alternator pulley slippage when moisture is high. Belt might be due for replacement. Hope this helps