No starter, no gauges, OBD2 not working either
#41
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I don't have the schematic in front of me so I'm just going by what most computer controlled circuits do these days. A relay has two circuits in it. One is the control side(coil) and the other is the LOAD side(High Currrent side which does the actual work). The coil needs 12Vdc and ground to make the connection on the LOAD side for the device(Starter) to work. When you turn the key switch 12Vdc is put on one side of the coil. If all the conditions the ECM says need to be met for the starter motor to work are met you will have ground on the other side of the coil. As I mentioned this might require the transmission to be in Park or Neutral or in the case of a manual the clutch may have to be depressed. There may be other conditions that have to be met as well. You need a schematic to be sure. Are you trying to do this blind? If so, good luck cause you'll need it. Better to play the Powerball instead Once all the ECM conditions are met you should have continuity between the chassis and one side of the relay coil circuit. You'll need a schematic to find out which side of the coil is HOT and which is ground. You do know what a continuity test is, right? You can also make the starter motor crank by putting a jumper wire between pins 30 and 87 with the key in the S position assuming the starter motor is good.
#42
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I don't have the schematic in front of me so I'm just going by what most computer controlled circuits do these days. A relay has two circuits in it. One is the control side(coil) and the other is the LOAD side(High Currrent side which does the actual work). The coil needs 12Vdc and ground to make the connection on the LOAD side for the device(Starter) to work. When you turn the key switch 12Vdc is put on one side of the coil. If all the conditions the ECM says need to be met for the starter motor to work are met you will have ground on the other side of the coil. As I mentioned this might require the transmission to be in Park or Neutral or in the case of a manual the clutch may have to be depressed. There may be other conditions that have to be met as well. You need a schematic to be sure. Are you trying to do this blind? If so, good luck cause you'll need it. Better to play the Powerball instead Once all the ECM conditions are met you should have continuity between the chassis and one side of the relay coil circuit. You'll need a schematic to find out which side of the coil is HOT and which is ground. You do know what a continuity test is, right? You can also make the starter motor crank by putting a jumper wire between pins 30 and 87 with the key in the S position assuming the starter motor is good.
#43
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Ok, next step is jump 30 to 87. Does it crank? Yes:Look for 12Vdc and ground on the relay coil pins 85 and 86 when key is in S position and all ECM conditions for starting are met. No:Test starter motor and associated wiring. I don't want to get you into trouble, but you can confirm your suspicion about the ECM not supplying ground. You have to be able to back probe the ground wire going to the relay coil. You'll have to lift the fuse panel from its' base to backprobe the wire. Put a "T" pin in the wire and take an aligator jumper from the "T" pin to chassis ground. If the ECM is failing to supply ground when asked to the puts the ground on the starter relay coil. If everything else is good the engine should crank when you substitute the ECM ground. If this jumper trick works you'll have to probe ALL the inputs to the ECM for the ground starter circuit. If they're all good the ECM is faulty. If not troubleshoot the missing input. There isn't much else left to check. This isn't a complex circuit by any means.
#44
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I just thought of something after rereading your last post. If you "hear" or "feel" the relay pick that doesn't mean the LOAD side of the relay is good, but the coil circuit(control side) is GOOD. That means the ECM is supplying ground when asked to and the key switch is supplying 12Vdc so don't waste your time troubleshooting the ECM ground feed because it is good. You problem is on the LOAD circuit which is even easier to fix.
#47
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What's that? I'm going to go back and check the ignition switch again tommorrow, but other than that there isn't much left. Battery is good, starter is new, ignition switch has been replaced, can't throw much more money at it. I'm still suspecting vats. I have it tuned out in the pcm but I'm wondering about the key now.I tried grounding the relay, but I'm not sure I was doing it correctly, I'm hesitant when it comes to cutting wires, usually thats a last resort.
Last edited by SuperC1; 03-10-2010 at 10:11 PM.
#48
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You don't troubleshoot with any consistency. Why go back over things you've already checked? The starter cranks when you jump 30 to87. What does that tell you? You said the relay energized when you turn the key. What does that tell you? Don't retrace those steps if you have PROVED those circuits are NOT the problem. What's left? The relay! Or you're not reporting your results correctly. Don't cut wires. I suggested using a "T" pin for backprobing. They are minimally invasive and you can repair the tiny hole they make with liquid tape or finger nail polish.
#49
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You don't troubleshoot with any consistency. Why go back over things you've already checked? The starter cranks when you jump 30 to87. What does that tell you? You said the relay energized when you turn the key. What does that tell you? Don't retrace those steps if you have PROVED those circuits are NOT the problem. What's left? The relay! Or you're not reporting your results correctly. Don't cut wires. I suggested using a "T" pin for backprobing. They are minimally invasive and you can repair the tiny hole they make with liquid tape or finger nail polish.