How to Troubleshoot a Car with No High Voltage Power Failure?
2 Answers
Methods to troubleshoot a car with no high voltage power failure include jump-starting, push-starting, or using another vehicle to tow-start. Jump-starting: Contact a rescue vehicle, connect the jumper cables, and temporarily charge the battery from the rescue vehicle to start the engine. This is the correct approach. To avoid being unable to charge when the car battery is dead, car owners should keep a set of jumper cables in their vehicle (available at any auto parts store). When connecting the jumper cables, it is crucial not to mix up the connection sequence: first connect the positive terminal of the dead battery to the positive terminal of the rescue vehicle's battery, then connect the negative terminal of the rescue vehicle's battery to a metal part in the engine compartment of the dead car (grounding). Push-starting/Tow-starting: In the absence of jumper cables, push-starting or tow-starting is the most familiar and effective emergency starting method. However, it should not be used frequently, as it can cause some damage to the engine and clutch. This method should especially be avoided for automatic transmission vehicles.
I've repaired many cars before, and the lack of high voltage is really a headache. Usually, I start by checking the battery—the voltage must be at least 12V, otherwise, everything else is pointless. Then, I use a test light to see if there's any spark at the spark plug. If not, it's likely that the ignition coil is faulty or there's an issue with the distributor. Older cars often have cracked distributor caps, leading to common leakage problems. Don't forget the related fuses in the fuse box—they can easily blow out, so check the manual for their location and replace them if necessary. Relays that squeak or don't work also need inspection. Loose connections in the wiring harness are common too. Last time, a car I worked on had a loose ground wire, and tightening it fixed the issue. Modern cars might have ECU control module failures, in which case you'll need a diagnostic tool to scan for error codes—guessing blindly is a waste of time and effort. After repairs, regularly inspect the wiring harness and connectors, and spray some anti-rust agent to extend their lifespan, which can save a lot on repair costs.
