Join Date: Oct 2013
Location: Chilliwack, BC, Canada
If only cranks when you short the two heavy starter relay studs (battery cable to starter cable) together, either the starter relay is not closing the contacts or the relay is not being operated by the starter button & safeties.
Can you hear the starter relay "click" at the times when the engine doesn't crank?
Also, could you clarify what you mean by, " dead the rest of the day"? Do you mean that that the starter doesn't crank the engine/ doesn't turn the engine? Just needing to make certain that I understand correctly as trying not to lead you into unnecessary testing.
If the starter relay doesn't "click", unplug the small two wire plug from the starter relay. Then, using your voltmeter red lead check from the battery positive to the Black/yellow wire in the two wire plug. Note, it may be better to probe the meter lead into the back of the plug rather than into the end which plugs into the relay. This is to reduce the chance of spreading the plug terminal.
You should show full battery voltage with the above test because the black/yellow wire goes to the common ground in the wiring harness.
If this test shows battery voltage, the likely cause is either an open circuit in the starter relay's magnetic winding (not common), stuck relay plunger (not common), or an open circuit in the starter button/safeties circuits.
The quick way to check the next stage is to plug the two wire back into the starter relay (while you had it off, you noticed whether the inside of the plug terminals and relay terminals were clean, right?), then use a jumper wire to connect momentarily from battery + to the back of the black wire in the two wire plug. **Make certain the transmission is out of gear because this will spin the starter and engine regardless of whether in gear.
If engine cranks then the starter button/safeties circuit will need to be explored. If the engine does not crank and the starter relay "clicks" the relay will need to be disassembled and cleaned or replaced. I clean them as they will usually last for many years after a clean.
If the starter relay does not "click" the starter relay plunger may be stuck or the magnetic winding open. An ohm meter test between the two small leads (to which the two wire plug connects) should indicate less than 30 ohms - going from memory as don't test them in this way. I prefer to simply jumper one of the small leads to ground and the other to battery +. Relay should "click". Ohmmeters can fool one in this kind of testing.
That should indicate either the fault as in the starter relay ground circuit- black/yellow; relay; or in the starter button/safeties circuit.
One needs be careful not to confuse the "starter relay" with the "starter circuit relay". The "starter relay" is the bigger one to which the starter and battery cable connect.
This is why technicians generally refer to the "starter relay" as the "starter solenoid".