Inside the solenoid are two contacts and a plunger, one of the contacts tends to burn out way before the other one, the contact ring on the plunger tends to burn badly too. Two contacts and a plunger are about $65 to supply new, we fit loads of them on Toyotas. They can be accessed by taking off the three 8mm bolts on the end cover. Make sure when you replace them you keep everything in the same order as there are "O" rings on the studs to keep the moisture out and make sure the plastic insulators are right too or you just get a bid short circuit.