2005 Nissan PathfinderJeremy Cato/The Globe and Mail
My 1993 Nissan Pathfinder seems to have an electrical problem. Sometimes when I turn the key it starts up right away, and other times when I turn the key there is a clicking sound, but no start. Sometimes it takes five or six tries to get it to start. I have changed the alternator but the problem persists. I am worried that one day I will be left stranded roadside. – Richard, Edmonton
"The fast answer is: the vehicle needs a new starter," says expert mechanic Patrick Brown-Harrison, an instructor at SAIT Polytechnic in Calgary. "There's not much else in the system that would react intermittently like that."
If you got that clicking sound and the engine didn't start at all, it could be a loose wire somewhere between the starter and the ignition switch. But because it's working on and off, Brown-Harrison thinks it sounds like the starter relay, also known as the starter solenoid. When you turn the key, the computer sends an electrical signal to the relay. Then, the relay does what its name says – it relays the high electrical current from the battery to the starter motor, which starts the engine.
"You can't put the high amperage that a starter requires through the ignition switch, so the relay is a low current switch to control a high current load," Brown-Harrison says. "Over time the contacts in the relay burn down from the high current travelling through them."
In modern starters, the relay is part of the assembly. To repair the relay you have to change the whole thing, Brown-Harrison says.
Starters don't last forever. A starter that's working only part of the time will eventually stop working completely. But starters don't always give such obvious warning to the driver. A starter that always worked fine could just stop one day. Brown-Harrison says regular electrical inspections can predict when a starter's getting closer to failing.
"One of the reasons repair centres offer electrical inspections is to test the starter," he says. "We know its going to fail as the current demand goes up."
If your Pathfinder starts fine with a boost, it could also be a sign that the starter is failing.
"All too often a battery is replaced because the vehicle needed to be boosted," Brown-Harrison says. "But it can actually be because the starter has gone high resistance and it needs more amperage, that's what the booster battery is providing."
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