2000 S10 no crank. Good starter, battery, ignition switch, clutch safety switch, fuses, relay, key cylinder. They're all new, plus I tested them in another 2000 S10. I can start it no problem by clutch popping OR using the paper clip in the relay box method. I've exhausted my capabilities. I'm thinking it's gotta be something between the ignition switch and the relay box? Advise seriously welcomed

what transmission, here. automatic or manual stick shift?
S10 not blazer S10

old cars this old (pre digital documents) are hard to find and when found are not complete. or poor .
A/T box?
the PRNDL switch must be good. and cranks in both Park and neutral.
yes the relay clicks too, if not the PRNDL is prime bad part.
there is fuse named CRANK.(1st inline here)
the starter can be hot wired (a test) to prove starter work.
if stick shift TRANNY it is called the clutch switch. to crank,
some books say hood up fire wall, center is relay. IDK


see why we ASK transmission first/
if the relay does not click the fuse crank blown
or PRNDL is dead only on P mode, try N.
if stick shift,, clutch CCP switch bad or just mal-adjusted.
ST below goes to the relay then to starter solenoid
the relay colors are there. Green or Purple.

PRNDL is on side of TANNY part of shift linkage.

A flat battery is the most obvious. Dash Lights take no power to light up, but starting needs AMPS.

Turn on the headlights, turn the key, do the headlights stay bright? If they do, the battery is okay. If they dim, it isn't.

Put the vehicle on a high end scan tool. It will tell you where the fault is.

Test Battery connections for continuity, if ok, use heavy duty test lead and connect live side of battery direct to starter motor.
If the engine cranks, the fault may lie between the ignition switch
and the starter solenoid.

I know you said it isn't the battery, forgive me, be sure the battery has a full charge and battery connections all good. Use a test lite and follow battery voltage. Battery ground is important also.
The battery voltage may lead to junction block--fusible links--fuse box?
At the fuse-box, pick any component that has a fuse, check fuse circuit for voltage, use a test lite. Some fuses are hot all the time, some go hot with key on, test both ways.
If the starter motor won't crank, check voltage and ground for the starter motor. Usually two voltage circuits at the starter motor, one comes from the battery, hot all the time. The other circuit goes hot with key in the crank position and is probably wired through the clutch or neutral switch then through the starter relay, where applicable, to the starter motor. The starter motor usually grounds through the engine block, so, battery negative connection is important.
Any testing at starter motor, make sure tranny is in park or neutral and functional parking brake is set. Safety is your responsibility. You don't want the vehicle to move during testing.

Can you jumper the solenoid on the starter and make it crank ?
Do you have power to the relay when the key is in the start position ?
Power goes from the key switch thru a crank fuse, then thru the neutral safety switch, then to the starter relay. The relay sends power from a 40amp ignition fuse to the starter solenoid.

This could be a couple different things causing your No-start condition. first thing I would check (Battery is good) access the starter solenoid, the small single wire connection is the start signal. Test for 12 volts here with DVOM or test light while someone turns the key. If there is 12 volts reading, the starter solenoid is defective. If there isn't 12 volts reading check all the fuses (with test light).
The second item causing the trouble could be the Neutral Safety Switch (Auto Trans) or Clutch Safety Switch (Manuel Trans) These could be open or out of adjustment.
Hope this helps you...

I will try to help, powell. Your start circuit from battery to ignition switch to starter-and back to battery. You may need to check every thing here, including the grounds, for a loose connection, or just possibly a failing part.
If only complaint is intermittent starter action, and no other problems with ignition switch, let's assume switch is good, so battery to ignition switch is good. Now from the switch, a yellow start wire goes to the instrument panel fuse block, to "crank" fuse #8 (10 amp), from there a purple wire goes to the safety switch. If manual it is a clutch pedal position switch (simple on/off switch-when clutch down switch is on). If automatic, purple wire goes to Transmission Range Switch on the transm.-in park or neutral the purple wire has continuity in and out of switch.
From that switch, the purple wire goes to the starter relay (under hood fuse-relay center). Now the relay: purple wire in start will energize the relay- wire goes to coil side of relay, and then coil side goes to ground. On relay power side, the power feed is a red wire-and it is the same red wire that initially sends power to the ignition switch. A 40 amp fuse in fuse-relay center sends power to ignition switch, and a splice goes to the starter relay as the power feed for relay. When relay is energized, contacts close, and power is sent from relay to the starter solenoid, again on a purple wire. When solenoid contacts close, starter motor is connected to the big battery cable on the starter.

There is your start circuit. try a new or different relay, try a new or test the clutch switch (or transm. range switch). Buy a $5 test light and use it to check where power is lost when starter won't operate. Hold key in start and check if fuse #8 is getting power. Check the safety switch, with key held in start, the purple wire should be hot. Check if relay has a power feed (pull relay out and check terminals) and if relay coil has a power signal in start. Check the relay's coil side ground. If that ground is intermittent, relay won't work.
When it won't start, use a test light, you should be able to find it.
Good luck.

Where is this relay? A wiring diagram doesn't show any relay at all in the starting circuit. Just this: a yellow start wire out of ignition switch goes to the neutral safety switch (if manual, a clutch start switch on the clutch pedal: if automatic a transmission range switch); From the safety switch a purple wire to the starter solenoid on the starter motor. Only other place to check is a "crank" fuse in the instrument panel fuse block- a 10 amp fuse in position 8 of the block.
Is the click you hear possibly from the starter solenoid? If it is, that means key switch part of circuit to the solenoid is good. Either starter motor is bad, or battery connections to starter and to battery ground may be bad, check them first.

Something wrong in the start circuit. The fact that dash lights come on indicates the ignition switch seems ok.- power is getting to it and exiting it.

The next place to check is the starter: before taking it off and have tested, do this quick test: when the car won't crank over, pull off the small wire on the starter solenoid-mounted on the starter-and see if that wire has power when the key is held in cranking position. You will need a helper to hold key in start, and an inexpensive testlight or volt meter to see if the wire has power.
This wire is the signal wire from the ignition switch to activate the solenoid and allow battery power to turn the starter motor on.
If the wire has power and still no crank, then the starter or solenoid is the problem, assuming battery and cables are good and connected tight. Pull the starter off and test it. If starter is good, probably the solenoid.
If the wire has no power when key is held in crank, the problem is in the circuit from the ignition switch to the solenoid-includes the neutral safety switch, maybe a starter relay, too. One would begin testing by checking for power on the start wire exiting the switch with key in cranking pos. If good there, test the neutral safety switcfh. If you have manual transm, the switch would be on the clutch pedal. If automatic, have a shop locate and test that.
Good luck- often, not always, it is the starter or solenoid. But do that check for power at solenoid , first.

Hi, diagnosing a no-start condition requires a logical approach to figuring out what might be preventing your car from starting. First, if the engine won't even crank over when you turn the ignition to START, your car obviously won't start.
When you turn the ignition key to start your car, voltage from the battery flows through the ignition switch to the Park/Neutral safety switch and/or brake pedal or clutch pedal safety switch (you have to push the pedal down before the circuit will complete) to the starter relay or solenoid. When the relay or solenoid is energized by voltage from the ignition switch circuit, it closes a contact that routes more power from the battery directly to the starter to crank the engine. The starter motor spins, pushes the starter drive gear to engage the flywheel and cranks the engine.

If the engine fails to crank, there is a fault in one of the components in the battery/ignition/starter circuit.

Ten Reasons why you car won't start..

1. Low battery (Check battery voltage, recharge if low, or jump start with another vehicle or battery charger).
2. Loose or corroded battery cables (Inspect, clean and tighten BOTH ends of BOTH battery cables).
3. Bad starter relay wiring connections or ground connection (Inspect, clean, tighten wiring connections).
4. Bad starter relay/solenoid (Check for voltage at relay, if relay has voltage but there is no "click" when key is turned to start, replace relay).
5. Bad starter (Jump battery voltage direct to starter to see if it spins, or remove starter and have it bench tested at auto parts store).
6. Damaged starter drive or teeth on flywheel (Remove starter and inspect drive gear and flywheel teeth, replace damaged parts if necessary).
7. Bad ignition switch (Check to see if voltage reaches starter relay/solenoid when turn to start. If not, check for open P/N switch and brake or clutch pedal switch. Replace ignition switch if defective).
8. Open P/N safety switch, or open Brake Pedal Safety Switch (automatic transmission) or open Clutch Pedal Switch (manual transmission). Bypass switch with jumper wire to see if engine cranks, or use test light or voltmeter to check for voltage passing through switch when ignition is turned to start.
9. Engine seized due to bearing failure or internal damage (Use socket and long handle to see if engine can be turned by hand, if not engine is locked up).
10. Engine hydrolocked due to coolant leak from leaky head gasket (Use socket and wrench to see if engine rotates, remove spark plugs and see if coolant comes out or engine can not be cranked with plugs out).

Hope it helps identify and solve the problem