My saaB 900s try to start But won't . I replaced every thing , Fuel pump, ignition coil, distriButor and ecu But car still wont' start. The engine light was on But after disconnecting the ecu and ICU, now when I connect an OBD II , I receive the no code message. What can it B? Timing Belt? The car cranks and really try to start But won't.

Use a flat screwdriver carefully to tap the lead down. Maybe put a cloth around the tip. Careful not to cause any damage.
Failing that... Meet a nice young girl with small hands.. Who knows ??

Your best bet , take it to a qualified repair shop. Your vehicle doesn't have a distributor cap . Has coil on plug ignition system ( four coils ) Or waste spark ignition system ( two coil's ) . You replaced parts needlessly . A qualified repair show could have fixed for the money you wasted . Viewing wiring diagram's an testing electrical circuit's , testing computer driver's ( what control the spark ) is how to diagnose . Not looking for a magical fix on here . Video's on youtube showing how to test computer drivers ( transistor's ) inside the ECU / ECM - engine computer . How to test B+ voltage to the coils , crank sensor input to the ECU / ECM .

wont start need help what can be the problem... ???? The problem is you shouldn't be trying to fix it . You have no clue

Your culprit is most likely an ignition coil, but could be so many different things, such as bad ground connections, bad ECU or simply the ECU fuse. Check all fuses to see if any are burned out. Check all wiring for corrosion. If your engine bay is nice and greasy that's probably NOT the problem. If it is rusty then likely a previous owner or dealer power-washed the engine compartment to make it look new. That's bad news because water pressure can get into almost any electrical device in the compartment, especially the ignition components. Check inside distributor. If you're lucky you may simply need to replace the rotor, if you have one. If not, it's an ignition coil.

Things to check:

1. Timing chain or timing belt (depending on which engine you have);
2. Coil pack or ignition coil (depending on which engine and year);
3. Rotor and distributor cap (if your Tahoe is an earlier model);
4. ECU (especially if you jump-started the car before the issue began);

check and test the coils and the points / ignition module. Check that the rotor button is not cracked . Check that the carbon button in the distributor cap is still spring loaded . Check that the HT wire to the distributor is operational

faulty crank position sensor is likely. No pulse from sensor to ECU, no activation of fuel pump, no fuel no start. The insulation in the inductive coil of the sensor breaks , and the sensor fails with age.

well seems i would normaly says its the coil but i have my fellings after reading all your info that you may have a dead short leadings to your coil, a dead ecu or a bad coil... hear is why if you replaced the relay and found 2 clicks then the system arched voltage back through the wire untill it fried your relay so i feel that your problem is after the relay, not before you will need a wireing diagram to test your wires, this is where i would start simply because its the cheapest thing to start with. once you have checked the wires if that is not it I can get you a test procidure to eliminating the ecu as the fualt I will have to have a little more info than just the modle and year... Modle, year, engine size, sohc, dohc ????
good luck let me know if you need more help

have your ignition coil checked, this problem happens when your ignition coil becomes hot and when you rest it cools down and it will work again. you don't repair ignition coil, instead you replace it with a new one.

Hello,1ºdesmount ignition coil and check if smeel burned,if coil is ok 2ºturn on ignition and listen if fuel pump is working(lift up back seat to listen better) or can be cranckshaft sensor(check with multimeter on OHM)

The most common problem is the Direct ignition cassette, followed by the crankshaft position sensor. I am assuming that it cranks, but won't start.