Q I have a '99 Lincoln Town Car that is afflicted by an intermittent battery drain. Whenever the air bag light is on while I'm driving, I have a dead battery the next morning. The last time this happened the battery would not take a charge until after I disconnected it. However, when the battery was connected there was a hissing sound, but it didn't hinder the starting. Do you have any suggestions?
A I hate to tell you, but this scenario is a bit scary. Anything that can kill the battery overnight and continue to draw enough current to prevent the battery from being recharged is a potential fire hazard. Assuming you're using a 6-10 amp battery charger, that means there's a current draw in that same range.
Clamp an inductive ammeter around the positive battery cable to determine how much current is being drawn after the ignition is switched off. Then, pull each fuse and relay one at a time to see if a specific circuit is the source of the draw. The fact that the symptom occurs when the air bag warning light stays on while driving may point to a problem with the headlamp/highbeam multi-function switch on the steering wheel and/or its harness running down the steering column.
Personally, I'd be hesitant to drive the vehicle until this problem is identified and corrected.
Q I own a 2002 Chevy Trailblazer with approximately 130K miles on it. While driving, the engine will stall. I can continue to hit the gas pedal and slightly increase RPMs until the engine finally stops. This only happens after it rains or it's extremely humid outside. It only occurs 1.3 to 1.5 miles into the drive from a cold start. Once I pull over, stop and restart the engine it will run fine all day. After happening for a few days the problem will disappear until the wet conditions occur again. I replaced the O2 sensor, No. 2 and No. 4 ignition coils (they looked rusty), the fuel regulator and the ignition switch. The SES light has never come on. Any ideas?
A The rusty ignition coils might be a clue. My Alldata automotive database pulled up TSB 06-06-04-048B dated January 2007 that identifies possible water leaks dripping on the engine cam cover, collecting around the ignition coils and seeping into the spark plug wells. A revised Air Intake Plenum with a foam weatherstrip seal has been released to prevent this water intrusion.
Since there are no DTC fault codes, TSB 03-06-04-057 from October 2003 suggests updating the programming for the PCM to reprofile the Evap purge valve test cycle that could cause lean operation shortly after start-up.
If the charcoal canister is soaked with fuel, this "open" cycle for the purge valve can cause a rich fuel mixture that the O2 sensor tries to adjust by leaning the mixture. If the purge cycle ends while this is occurring, the engine is temporarily too lean and may stall. Cycling the key resets the system, allowing the engine to return to normal operation.
Q The cruise control on my 1987 Bronco drops out when I turn on the headlights. Otherwise it operates fine. Could this be a voltage drop problem via a bad connection due to headlight amp surge, or is something else happening?
A I think you're on the right track. I suspect the harness from the multi-function switch in the steering column has a frayed, worn or open connection. Otherwise, make sure the brake lights are not coming on with the headlights -- this would cause the cruise to drop out or not engage.