I have a 1999 chevy tahoe that I recently purchased. It runs great but for some reason it has to be jumped off to start. I thought the battery was bad so I bought a new one. I still had to get a jump. Then I noticed the security light was on and searched google and everything told me it was the passlock system. So I had a locksmith come out. He was able to start it with a jump and informed me that the issue was not the passlock. So what could it possibly be? After I get a jump it runs perfectly, and if I cut it off, I can turn it right back on, but after leaving it off for a while it does not start again without a jump.
Last edited by 2011nfl (2/28/2013 8:05 PM)
Have a mechanic check the charging system first making sure it is charging at the recommended voltage which is between 13.0v to 14.4v. Then he should check for a parasitic drain on the battery.
He should also check to see if there any trouble codes stored in the PCM related to the charging system.
The recommendation for maximum parasitic drain is around 30 mA (0.030 amp). A typical drain today actually falls into the 7-12 mA range, even though some vehicles do approach the maximum.
If the parasitic draw exceeds the maximum limit then check for a glove box light staying on, luggage compartment light. PCM not powering down, the list can go on. The mechanic will know where to look depending on how much the draw on the battery is.
If the charging system checks out to be good and there is no parasitic draw then check all of the body grounds and electrical connections for proper voltage drops (poor connections).