Turn the key and nothing happens. But, I can turn the switch to on and cross jump the relay and start the engine.
You could have any number of defects causing this problem.
If the starter works when you short across the relay, it's clearly not that, but it cloud be the relay itself, which is not uncommon. You can test to see if the relay is engaging by supplying electrical power to the smaller positive connecter on the relay using a piece of wire direct from the battery. If that works your problem is in the electrical supply from the starter switch, which is usually part of the ignition switch. For example, if you engage the start position with the ignition on, you should get an electrical voltage at the small terminal on the starter solenoid that you previously shorted with the bit of wire. The starter circuit will be protected by a fuse or circuit-breaker, if the problem is with the electrical supply to the solenoid/relay then you need to check the starter fuse or circuit breaker. If the fuse looks intact you need to check it with a meter as looks can be deceiving. If the fuse checks out as good then the problem is either the starter switch failing to make a good contact or a break in the wire between the switch and the solenoid/relay.
If you decide to check the starter switch, it is not uncommon to find a voltage at the switch but due to bad or dirty contacts in the switch, insufficient electrical current will pass to engage the solenoid/relay. This will of course be the same when you check for electrical supply to the relay, that is why you need to try to engage the relay with a remote bit of wire. Unless you can dismantle the switch and clean the contacts you may need a new switch. So, check the wire from the switch to the relay. If you remove the small positive wire at the relay and attach your remote power supply to the end of the wire, taking care to insulate the connection to prevent it shorting on anything else, you should get an electrical power reading on your meter at the start switch. If you don't you have a broken wire or connection. Sometimes it's easier to run a new wire and isolate the old one, if this is the case and you can't find an obvious break in the connection. Rgs. Bob
Jun 21, 2015 |
Cars & Trucks