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Engine won't crank, not VATS, clutch safety switch, battery
Hello there. I have a 1998 firebird formula with the LS1 and a 6 speed manual. I was driving it last night, shut off the engine, went into a friend's house for 5 to 10 minutes, then came back out and it wouldn't start. All the electronic systems started up as normal when turned to the on/ignition position. However, when I turn the key to the start position, nothing. No clicks or anything.
The car will still run. Luckily, we were at the top of a hill and I had guys with me to push start it (thank God for manual transmissions!). Got er rolling fast enough then let out the clutch in second with the key in the on position. It started right up and ran fine, so the problem isn't an alternator or battery.
It's not the Anti theft system with the resistor in the key. I went to radio shack today, measured the resistance to find the correct value of key, and then bought the corresponding resistors to hook up in series and get the right value, or a value that should be close enough to make it work.
It's also not the clutch safety switch, which was my second guess. I took it loose from the bracket and tried to start the car with the button both pushed in, and not pushed in. Neither worked. I unplugged the switch from the wires and tried to start it. I then took a wire and closed the circuit and tried to start the car. No luck with any of that.
All the fuses on the car, both on the side of the dash and under the hood, are good. None are blown. I had a friend turn the key while I was under the hood. When he turned the key to the on position, I felt the ignition relay click. But when he turned it to the start position but I felt no click from that relay. This leads me to believe the problem is either before starter relay or the starter relay itself, which rules out anything such as the starter being bad or the solenoid on the starter being bad.
One last piece of information. I was messing around with the clutch safety switch while plugged in, switching it on and off while trying to turn the key. It started up once and ran fine, then when I shut it off and tried to start it again, nothing happened. When this happened, the resistors I got from radio shack were not plugged into the wiring harness, giving even more proof that it's not the VATS system.
So here's my question: What else could it be? If it is a short in the wiring or a bad connector, does anyone have a wiring diagram of the starter system so as to adequately troubleshoot where it could be?
Do you know what the color of the wires would be I would need to check to see if they're making a connection? Because there's a huge mess of wires coming down the steering column.
The starter is not the problem. I and a friend were working on it all of today. We were able to jump the starter with a wire and it cranked. It's definitely not the relays either. I switched the starter relay with the ignition relay and no dice. We then jumped the terminals on the starter relay and it started right up. We then measured the voltage across the two terminals that actuate the starter relay and they were about .08 volts. So for some reason this circuit isn't getting enough juice. It's a yellow and black wire and we don't know where it comes from. We had an inkling and looked at some wires on the body control module. There was a yellow and black wire on the connector there and we measure the voltage across it and a ground and it was also .08 volts. So my question to you guys is, what wire going INTO the body control module corresponds with this yellow and black wire coming OUT of the body control module? I'd like to be able to measure the voltage across it to find out if the problem is before the body control module or after it. This means the issue is somewhere between the clutch switch and the BCM.
You've made a few invalid conclusions but it's good to see someone actually troubleshooting instead of just throwing parts at a problem.
The yellow/black wire at the starter relay corresponds to the yellow/black wire at the BCM. It is the ground wire for the starter relay coil. Ignition switched power passes through the clutch switch (neutral safety switch in an A4) to the starter relay coil via the dark green wire. The VATS in the BCM controls the relay coil ground through the yellow/black wire - when VATS is satisfied that the correct key is used, it provides ground for the starter relay coil so that the ignition switch can trip the relay and run the starter.
You should test that you get full voltage on the dark green wire when the ignition is switched to the START position and the clutch is disengaged. If so, ground the yellow/black wire to complete the circuit and see if the starter runs. If it does then you have a problem in the yellow/black wire to the BCM or with the BCM itself (i.e. VATS). If it still doesn't crank then the relay is bad.
So what does the orange and black PNP wire coming from the ECM to the console do (98)? I thought this had something to do with the neutral safety switch too??
So what does the orange and black PNP wire coming from the ECM to the console do (98)? I thought this had something to do with the neutral safety switch too??
PNP is just GM's fancy name for a neutral safety switch. The orange/black wire is part of the Park Neutral Position circuit but it is not involved in starting... it is there for various PCM control functions such as torque management and idle management. Two other wires on the PNP switch handle the starting duties - the purple/white wire provides input power and the dark green wire carries power to the starter relay when the switch is in the park or neutral positions.
Of course, this doesn't apply to the original poster's manual transmission.
Okay guys, I feel like an idiot for wasting my time and yours. Last night after talking to my father, I found out that I was looking at the wrong "clutch switch." I couldn't figure out why the clutch switch would be in series with a switch on the brake, so I talked to my dad and he suggested it was probably to disengage the cruise control. I didn't even think about this! My cruise control doesn't work, so I guess I'd completely forgotten it was there at all. Today, I went to go and look for the correct clutch switch that was wired to the starting circuit. I located it, took the connector loose, closed the gap with a piece of wire, and lo and behold, the car started. So I guess it was the clutch switch all along. Sigh. So my next question is, does anyone know what the part number for this switch is and where I could get one at? Would any of the major auto parts stores (o reilly's/auto zone/napa/etc) be able to order in this switch, or will I need to go to a GM dealership? Or would it be cheaper online? Thanks so much for all the help guys! I really appreciate it!
You've made a few invalid conclusions but it's good to see someone actually troubleshooting instead of just throwing parts at a problem.
The yellow/black wire at the starter relay corresponds to the yellow/black wire at the BCM. It is the ground wire for the starter relay coil. Ignition switched power passes through the clutch switch (neutral safety switch in an A4) to the starter relay coil via the dark green wire. The VATS in the BCM controls the relay coil ground through the yellow/black wire - when VATS is satisfied that the correct key is used, it provides ground for the starter relay coil so that the ignition switch can trip the relay and run the starter.
You should test that you get full voltage on the dark green wire when the ignition is switched to the START position and the clutch is disengaged. If so, ground the yellow/black wire to complete the circuit and see if the starter runs. If it does then you have a problem in the yellow/black wire to the BCM or with the BCM itself (i.e. VATS). If it still doesn't crank then the relay is bad.
I have a question...I know this is an old post but I'm having starting problems all of the sudden. This explains my situation perfectly except for the fact that my clutch switch is good. I don't have any power to switch my starter relay and it has the bypass for the VATS. Granted I hate how it's done...I just bought this car and the prior owner has a cluster f**k of wiring issues in my opinion. What if I'm not getting powe from the clutch switch green wire? Where should I look? Many more questions and I'd like to post pictures but I'm new and don't know how :-(
Let's start with some diagnostics at the starter relay. There are four wires at the relay:
Dark Green - battery positive voltage from the STRTR 15A mini fuse in Junction Block #2 via the clutch switch (or PNP switch in an automatic)
Red - battery power from the IGN 50A MaxiFuse in Junction Block #2
Yellow/Black - starter relay coil ground controlled by the BCM (VATS)
Purple - starter relay output to the starter solenoid
To save time, the first thing to check is the STRTR 15A mini fuse. Never rely on a visual inspection (especially of a 13+ year old fuse) - it could be blown but still look fine. Use a tester or replace with a known good fuse. Do the same with the IGN MaxiFuse although if it was blown, basically nothing related to the ignition would work so it's probably fine.
Now if that didn't solve the problem, we start checking with a test light or multimeter. In this case a test light will be simpler since we don't have any computerized or solid state components to worry about and we only need to test for the presence of power or ground.
Test for constant power on the red wire. If no power, look for a break in the wire someplace between the IGN MaxiFuse and the relay.
Now you will need a helper. Have them in the car ready to try the starter when you are under the hood testing. Check that the dark green wire gets power when they try to crank the engine. If not, either your clutch switch or the wiring between the fuse and the switch or between the switch and the relay is bad. At the clutch switch, check for input power on the purple/white wire then check for output power on the green wire when the clutch pedal is depressed. That will determine if it's the switch or which side of the wiring.
Back to the helper. Check for ground on the yellow/black wire at the starter relay when the helper tries to crank the engine. If no ground, either you have a break in the wire from the relay to the BCM or your VATS is preventing the ground (although the SECURITY light in the instrument cluster should be illuminated or flashing if VATS is the problem).
Those steps should help you nail down where the problem is located. Don't assume anything - always test to confirm.
I have been reading through the posts here and this is exactly what our Firebird is doing. We are not getting power on the purple wire when we try to start the car.
We have tried popping the clutch, nada
Tried charging the battery 100% - Nada
Tried bypassing the batter all together - nada
Tried leaving it with key in the ignition for a few hours - nada
Not sure where the BCM or Clutch switch is on this vehicle to check for sure. We have the means, to check, but would rather know where to look than taking apart more than we need to.
The car drove fine. We parked it for a couple of days and went to drive it today, and it wouldn't start. No clicking, all lights on the dash work, security light is blinking fine, radio, all lights on the dash come on fine.
Any ideas? I keep getting bits an pieces of things to try. If anyone can help it would be greatly appreciated.
The process for diagnosing the starter relay is listed in the post immediately above yours. The starter relay is in junction box #2 under the hood on the left wheel well. Pull the relay and use a test light or multimeter to check for power and ground for each of the four connections in the relay socket as listed.
The SECURITY light in the instrument cluster should not be "blinking fine". That indicates that the Vehicle Anti-Theft System (VATS) cannot see a resistor in the ignition key. The light will be on solidly if VATS sees a key resistor with the wrong value (wrong key) or it will blink if there is no resistor found. During normal operation, the light should be off.
The blinking light indicates either a damaged key, a damaged ignition cylinder, or a broken wire somewhere between the ignition cylinder and the BCM. In that case, you will find that there is no ground available on the yellow/black wire at the starter relay because VATS is actively preventing starting.
The clutch switch is on the clutch pedal bracket positioned to open the circuit when the pedal is depressed. No need to crawl under there and check unless you find no power on the dark green wire at the starter relay.
The BCM is a black box about the size of a paperback book mounted to the HVAC housing behind the glove box on the passenger's side of the dash. No need to access that unless you find no ground on the yellow/black wire at the starter relay and then only after you have fixed whatever is causing the flashing SECURITY light.
Thanks WhiteBird00. I will have him try these steps this afternoon. Now that I think about it, yes, the light should be solid.....I believe he checked the clutch switch already after I had posted this, but will double check. Thanks again!
Whitebird - We have done the following on the 2002 Firebird -
- checked the starter Relay - Good
- Clutch switch - Good
- Power to fuse - Good
- I was wrong on the light - Security light on dash goes out as expected when switch is turned on
- Changed out the BCM and the car will not acknowledge - Is that a programmable part and does it have to be done by dealer or can we program or does it program itself?
Don't have a ton of money to put in this car, have had it for 15 years.....love it and would like to drive it again. I really appreciate your help . Thank you in advance!
If the ground on the yellow/black wire checked at the starter relay then there is no reason to consider the BCM. Just put the original BCM back. A brand new BCM will automatically program itself to the first ignition key used and can never be reprogrammed after that. So a used BCM won't work unless you get the key that matches it or you do a VATS bypass by trial-and-error with each of the 14 possible key resistor values until you find the one that matches.
When you say you checked the starter relay, did you check the wire connections to the relay or just the relay itself? If both the relay and the connections tested as good (using the conditions I posted earlier) then you either have a broken wire between the relay and the starter or the starter itself is dead.
If you haven't tested the connections at the relay then go do that first. It's impossible to diagnose without knowing those results.
Sorry to bring back a dead thread, but I thought I'd add the answer to my problem in case it helps someone else.
My 2002 SS drove fine at lunch. Parked it. Came out of my office after work and it would start. No cranking, not the usual dead battery clicking. I checked all underhood fuses, they were ok.
I have a wire that parallels the purple starter wire. With the key in the ignition in the on position, I am able to touch the positive battery post and the car starts. Drove it home, but get this no gauges (other than oil pressure) work. No speed, tach temp, voltage. Nothing. Also auto headlights didn't come on (it was night time).
This morning I looked at the fuse panel on the left side of the dash and found the 10A red fuse for gauges blown. Changed it out and the car starts up and behaves as normal.
I hope this might help someone else in the future.
I'm putting a Holley ECU on my car and I need to ground the VATS to get my key to work. This yellow wire I'm holding in my finger, is this the one you're saying to ground? Its solid yellow, not yellow/black but it seems to be the one that whitebird is talking about. I was just wanting a confirmation before I go ahead and cut it. This is also on a '99 not a '98
09-05-2010, 04:24 PM
Engine won't crank, not VATS, clutch safety switch, battery 
2002 Firebird Formula Won't Start 
