Top of the Mornin to Ya!
Today a customer learned a very difficult lesson!
The story starts last night when the customer came home, parked the car in the garage and went to spend time with the family. Just one little mistake, the customer had turned on the headlamp override switch. This bypasses the automatic shutoff feature! Of course the next morning while in a hurry to get to work, the customer found the battery “Dead as a door nail!” The customer jumped to action and connected a standard 10amp battery charger and rushed off to the daily grind. At lunch time the customer got a ride home from a coworker expecting the battery to have been recharged and ready to go!
Surprise!!! The engine still would not crank!
Now assuming that the battery was bad the customer had the vehicle towed into my shop. Remember what they say about ass/u/me! Whoops should not have said that!
Our technician charged and tested the battery, which passed with flying colors!
Guess what? The car engine cranked over just fine but would not start! Further testing revealed that the computer would not communicate with our scan equipment, nor would it turn on the fuel pump, injectors or anything! After replacing the computer or ECM (Engine Control Module) the car started and performed perfectly!
So what happened? Any guesses?
Hope this keeps the brain cells busy!
Harold Wood
President
Harold’s Quality Auto Repair Inc.
PS: I let you know next time!
admin says
March 19, 2009 at 5:39 pmSupplement To Learned the Hard Way.
Hi Everyone,
Since no one has been able to answer my auto repair brain teaser I am going to share just a little more information.
The customer showed us how they had hooked up the charger and we determined that it had been connected properly!
One more hint the key had been left in the ignition.
Ok now that you have wrapped your brain around this new information any guesses?
Harold
admin says
March 20, 2009 at 7:27 pmWinner!!!!
Hi everyone!
Well you can quit racking your brain for we have a winner!
Congrats to Dave Smith of Liberty Systems for giving the correct answer to the auto repair brainteaser!
Heh Dave give the shop a call at 503-365-9702 and set up an appointment for a FREE Lube, Oil & Filter!
Oh I almost forgot, the correct answer was Low Voltage!
As the charger raises the voltage up enough, (and with the key in the ON position)
the relays that are used to activate various circuits with the ignition switch, now turn on.
The load, which is applied, is more than a 10amp charger can put out.
So the voltage goes down again.
When the voltage drops low enough the magnetic fields in the relays weaken and cause
the relay to open the circuit and again the voltage goes up.
This process repeated itself over and over again.
So the battery never recharges and the computer is subjected to repeated startups with insufficient voltage
and the small voltage spikes did not help either!!
Have a great weekend!!!