The ability to take proper measurements is required to help diagnose many conditions or problems with your Pontiac. Measuring the electrolysis of the coolant or the dwell on an HEI ignition module can assign accurate, hard numbers as to its condition and eliminate the work, embarrassment, and expense of changing parts as a diagnostic step.
The skill of measuring is not hard to master but sometimes requires special tools, such as a dwell meter, voltmeter, or infrared thermal heat gun. The decision of which tools to invest in will have to be yours, along with learning to use them. The purpose of this primer is to show the basic steps of how to take a few pertinent measurements on a Pontiac. Hopefully, this will enable you to get to know your Pontiac better and keep it in top condition.
For our photos, we worked with Joey Jaramillo of IDA Automotive in Morganville, New Jersey.
Tool required: Volt-ohm meter
Resistance in a circuit is opposition to current flow. To check the resistance of a circuit, make sure it’s not powered and remove it from the circuit (unplug it). Place the meter on the ohm scale and connect the two leads across the circuit. An ohm meter has no polarity so it makes no difference which lead goes where. When checking a circuit for continuity, an open circuit will read infinity or over range since there is no complete path. You can use this test to check a light bulb or any other electrical part such as an ignition wire or a coil. This is a very good test for late-model Pontiacs with DIS ignition and coil packs.
Tool required: Volt-ohm meter
When checking battery voltage, the meter needs to be connected in the proper polarity. A good battery when at rest will have around 12.6 volts. That is called the surface charge. As the cells begin to sulfate, the voltage at rest may actually go higher to around 13.1, but its capacity is diminished. To check a Pontiac’s battery, place the meter across the battery terminals. With the ignition disabled, have a helper crank the engine over. The battery should have enough capacity to keep the voltage above 9.6 for an extended crank of 10-15 seconds. If it does not, it’s weak and needs to be replaced before winter.
Sticking Brake Pad or Shoe vs. Frozen Caliper or Wheel Cylinder
Tool required: Infrared thermometer
Go for a short drive at a speed above 35 mph. Gently stop the Pontiac in a safe place on the shoulder of the road or back at home. Quickly go to each wheel and through the rim (if equipped with wheel covers, they will need to be removed first) measure each disc or drum in the same spot with an infrared thermometer to measure the rotor and or drum temperature. They should be within 10 percent front to front and rear to rear.
If one is very hot, then that pad or shoe is hanging up. A very cold reading indicates the caliper or wheel cylinder may be frozen or hardly moving. Frozen rear calipers were a complaint of some owners of Second-Gens and Third-Gens equipped with rear disc brakes.