1. The alternator came with a plastic “hat” on the top post. If yours is gone, the wire harness will sit on the post and the post will dig into the wire harness. The result will be various malfunctions. It happened to me. The harness had a deep hole in it. I filled the hole with rtv and cured the problem.
2. The large white connector to the rear of the battery gets moisture. Pull apart (clean where necessary) and put it back together. This connector is associated with many electrical problems.
3. Remove the ground strap at the top of the tranny, Clean very well. Replace. Also remove the ground connection on the same cable where it connects to the body and clean. Best bet=replace the cable.
4. Starter electrical problems. Replace the positive cable. Most are corroded badly by now. Replace the smaller wire on the starter (ignition wire). This wire is also corroded badly and gets overheated by the exhaust. Don’t fix, replace.
5. Remove and clean the ground wire close to the alternator. Adding additional ground straps is always a good idea.
6. Replacing the connector for the alternator top post is a good idea. Through the years of replacing alt. the wires tend to break at the connector.
7. The smaller wire on the battery positive cable is a fusible link. It should be replaced as age and corrosion can create all manner of problems.
8. Rule of thumb for electrical problems=it’s the ground connection
9. Use a volt meter on the battery. Ignition off=12v engine running=13.5 to 14v.
10. Injector wire connectors sometimes pop off. A carefully placed dab of rtv between the connectors will hold them on.
11. If your car doesn’t start after you washed it, there is likely water in the valley of the valve cover causing a short. Clean it out and try again.
11.1. Do the same thing with the Distributor cap, remove, dry and put back into place.
12. If three of your dash lights(just the engine cooling fan, charge, and brake) flash on or stay on while the car is turned on or while driving then test your alternator because it usually means it’s bad!
This documentation in no way replaces the Toyota MR2 Repair Manuals. The purpose of this content is only to provide supplementary information to fellow MR2 enthusiasts. Midship Runabout and its contributing authors will not be held responsible for any injury or damages that may occur as the result of practicing any of the methods or procedures described within this website. Article and photo submissions are property of the contributing author.