* Loose or corroded battery cables: This is the most common culprit. Check both ends of the positive (+) and negative (-) cables at both the battery and the connection points on the vehicle's chassis. Look for corrosion (white, green, or blue powdery substance) and ensure the clamps are tight and making good contact. Clean any corrosion with a wire brush and baking soda solution.
* Bad battery: A weak or failing battery can cause erratic electrical behavior during jump-starting. Even if it *seems* to have enough charge to crank, internal issues can lead to chatter.
* Faulty alternator: A malfunctioning alternator might not be providing sufficient charge, resulting in unstable voltage and the chatter you're experiencing.
* Faulty voltage regulator: The voltage regulator controls the alternator's output. A faulty regulator can cause the alternator to overcharge or undercharge, leading to electrical issues.
* Wiring problems: Damaged, frayed, or loose wiring anywhere in the charging system can create intermittent connections and chatter. This is harder to diagnose and may require a more thorough inspection.
* Poor ground connection: A weak or corroded ground connection (the negative cable) can lead to erratic electrical behavior. Check the main ground cable connections to the engine block and the chassis.
* Faulty starter: Though less likely to directly cause chatter during the jump-start *process*, a failing starter could exhibit symptoms like this in conjunction with the jump starting, and be a contributing factor to a problem elsewhere.
Troubleshooting Steps:
1. Check and clean the battery terminals and cables FIRST. This is the quickest and easiest fix and often solves the problem.
2. Visually inspect all wiring related to the battery and alternator. Look for any signs of damage or corrosion.
3. Try jump-starting again after cleaning the terminals and cables. If the chatter persists, move to further diagnostics.
4. Have the battery tested at an auto parts store. They can test the battery's capacity and determine if it's holding a charge.
5. Have the alternator and voltage regulator tested. This usually requires a professional mechanic or auto parts store with diagnostic equipment.
If you're not comfortable working with car electrical systems, it's best to take the van to a qualified mechanic for diagnosis and repair. Attempting repairs without proper knowledge can be dangerous.
