Here's a photo from rockauto. Com of the starter relay. It looks like that might be it in the left photo. I remember the newer version with all plug-in wires. Yours has a stud that connects the battery positive cable to the starter cable. On newer models that is all one cable, and a smaller second one goes from the battery positive post to the relay. Just a different way of doing the same thing.
The entire starter system can be broken down into four parts, each with a test point at that relay. A digital voltmeter will work but in this case a test light is just as accurate, and maybe even more so. Ground the test light on the battery negative post. Two terminals on the relay should have voltage. That large stud must have full battery voltage all the time. One of the smaller plug-in wires must have battery voltage when a helper turns the ignition switch to "crank".
Move the test light's ground clip to the battery's positive post, then probe the other two terminals. The light should light up on both of them indicating current has a path to ground. If the plug-in terminal doesn't light up, that is the circuit going to ground through the neutral safety switch. Since you replaced the switch already, (which is a low-failure item), look for damaged wiring to it. The smaller bolt-on terminal goes to the starter solenoid. About the only thing that might go wrong with that is a loose smaller wire on the starter or the wire is broken or corroded right at the terminal.
Here's some hints. If that relay clicks solidly once each time a helper turns the ignition switch to crank, the control circuit is working. That means the ignition switch and neutral safety switch are working. If it doesn't click, first pull off those two plug-in terminals and check if they're rusty. Wiggling the terminals will scratch them enough to create a clean spot that might work temporarily, but the real fix is to shine them up with sandpaper and possibly replace the terminals.
If the relay doesn't click, you can verify the rest of the system is working by using a screwdriver blade to jump between the two bolted-on wires on the relay. If the starter cranks the engine, you know the battery, cables, connections, and starter are okay.
If the relay DOES click, use the test light, grounded to the negative battery post, and probe the smaller bolt-on terminal. You should see full voltage there when the relay clicks on. If not, the relay is defective. Here again, jumping the two bolt-on terminals with a screwdriver will crank the engine. If there IS voltage there but your new starter doesn't engage, a rare problem is one of the two solenoid coils is open. Electrically the solenoid will test good, and it might work fine during a bench test, but on the van the magnetic field strength from both coils is needed to get the solenoid to engage. A hint to finding this confusing problem is very often the starter will work normally when a large battery charger is connected. The higher voltage causes higher current flow which creates a magnetic field that is strong enough to engage the solenoid when only one of those coils is working. Those coils don't typically burn open on their own. One of the wires can break off from rough handling when someone has it apart for other service.
Another hint is to watch the brightness of the head lights when trying to crank the engine. If they go out, suspect a loose or dirty battery cable connection. There are other tests we can do to pinpoint which one that is. Also be sure the smaller black wire from the battery negative cable is bolted securely to the body.
Friday, July 22nd, 2011 AT 12:39 AM