Testing Ignition and Safety Switches for MTD mower
I have an MTD model 673 riding mower with a Briggs 2 cylinder engine (model 42A707 type 2238E1 code 9902055A). It won't turn over when the ignition switch is turned. However, I jumped the starter solenoid and the engine turns over OK, so the starter and battery are good. This was a sudden problem - ran the engine a week ago.
Using a test light(and with both the blade, clutch and seat safety switches closed) I get no light when I turn the key on and touch the test light to the solenoid terminal going to the starter, and no light when the key is turned on and I touch the single spade terminal from the ignition switch. The solenoid ground is good. It would seem there is a problem with either the ignition switch or one of the safety switches since I'm not getting current to the solenoid with the key on.
The seat switch is a simple "ground out" - when you sit on the seat it breaks the metal contact (easily visible, not a button switch.) I manually pushed in the buttons on both the blade and clutch switches, so either there is an internal lack of contact within these switches or else the ignition switch is bad.
I removed the ignition switch (5 terminals marked G, L, M, S and "blank" - I assume "blank" is the Bat terminal?) and tested for continuity. With the key in the off position I get continuity between L and "blank". With the key in the on position I get continuity between S and blank. If S is starter and blank is battery, then it would seem the ignition switch itself is OK because I'm getting continuity between S and blank (battery?) When I use the test light at the wire connectors for the ignition switch terminal (with clutch depressed and blade lever up), I get no light on any of them (shouldn't one of those five wires at the ignition switch be a hot at all times???) I can't see any damage to the wiring.
If either the clutch safety or blade safety switches aren't working, would this prevent current from reaching the ignition switch? I used the test light probe on all the safety switch wires (clutch safety= yellow, yellow, white, orange, orange; blade safety = orange/white, orange/black, yellow, yellow, yellow) and get no light.
The wiring diagram in the MTD parts book is virtually useless - no clear idea where the wires connect, wire colors don't totally match what I have, no indication where fuses might be).
Any help in figuring out which component is responsible and how to further test the ignition, clutch and blade switches or discover where the fuse links are would be appreciated!