Mach won't start

[GrimlokTT]

As Orange mentioned, you can check for parasitic draws. As test lights are quick indications of this draw, they shouldn't be the deciding factor. As Orange mentioned, the light can still glow due to onboard electronic components. How brightly depends on how much of a draw you have. (Make sure you have the doors shut and the key is off when you do this.) What you need to use is a multi-meter to see if that draw is w/n limits. (I believe it's b/n the negative cable and negative post when disconnected?)

Regardless, I'm guessing you have a crappy battery versus a parasitic draw.

Name ____________________† Instructorís OK ______
Vehicle # _____ Make ____________ Model __________ Year _____



Battery Diagnosis Worksheet
1. Visual Inspection and Electrolyte Level: Check battery for corroded terminals (warning—it’s what’s on the inside that counts), loose or broken clamps, cracks, leaks, low electrolyte level, missing vent caps, missing or bad battery hold downs, correct size and capacity for vehicle, built-in hydrometer and acid powder on top.
Terminals need cleaning ___ Terminals have been cleaned ___
Electrolyte level is OK ___ Electrolyte level is too low ___ Other problems __________________________________
2. Determine State of Charge: Is battery up to 70% so it can be tested?
Using hydrometer: measure specific gravity of all six cells and record here: ____ ____ ____ ____ ____ ____
Are all above 1.240? Yes ___ No ___
Is there a difference of 0.050 or more between cells? Yes ___ No ___ (if yes, replace battery)
Using digital voltmeter: Remove surface charge by 1) turning on headlights for 3 minutes ____ or load testing battery 100-200 amps for 15 seconds ____. When battery voltage comes back up, where does it come to? 12.6v (100%) ___ 12.4v (75%) ___ 12.2v (50%) ___ 12.0v (25%) 11.8v or lower (0%) ___
Battery is ready to load test ___ Battery needs charging ___
3. Load Test Battery: (Capacity Test) This tests if the battery can put out enough volts and amps, that it is not sulfated. Hook up tester so you measure the amps going through the carbon pile and volts.
CCA rating ______, divided by two = ______.
Load test at this amperage, (but not too much more than 200 amps) for 15 seconds, and record the voltage at 15 seconds here: ______
Voltage is above 9.6v—passes ___ below 9.6v—fails ___
4. Check Parasitic Draw when battery turned off. Connect amp meter in series, should be no more than 0.050 amps or 50 ma after the computers have shut down.
How much? ____ OK ___ Not OK ___
5. Use Capacitance Tester. Follow instructions on screen
Pass: ____ Fail: ____ Readings: ______________________________

[Orange whip 04]

(I believe it's b/n the negative cable and negative post when disconnected?)



QUOTE]

There has been controversy as to how its actualy done. But it acutaly can be done both ways. I get the same results if i do it from the negative side or positive side. I like to do it from the positive side because it tends to rule out any possible grouding iregularities. As you mentioned, you can use the volt/ohm multimeter to check how much voltage is acutaly draining. I use a test light because its simple and iam so acustom to what iam seeing shine through the light and knowing what is being used onboard Ford models that it becomes second nature to me to make a repair knowing what it causing the problem. But in any other case normaly a meter would be used to measure voltage use. This goes back to the words... How do you measure the draw of a light? Once i have ruled that a system has a lagitament parasitic draw, i start to narrow the circuit down by pulling fuses out of the fuse box one at a time and put them back in until you notice the light that is shining through the test light goes out when the fuse was pulled for that slot. Once you find the circuit that the draw is on then you can narrow down through the wiring or part that may be causing the short to ground. Its a process that can take 5 minutes or 5 hours. With electrical, you never know what bag of worms you have. But i also agree with you, Granny probably just has a crapped out battery.

[justin2050]

my battery keeps dying because my brake lights are stuck on they wont go off.... could this be caused by a blown or loose fuse or should i just wait for my appt. at the dealer next week.

[substanger]

Originally Posted by justin2050

my battery keeps dying because my brake lights are stuck on they wont go off.... could this be caused by a blown or loose fuse or should i just wait for my appt. at the dealer next week.

Bad brake pedal switch.