No start

dastrups

Well-Known Member
Hey guys. A couple issues here. When I press in the clutch and turn the key I get nothing but a click. When I jump the starter it will fire over for a split second and then die. The starter is brand new and working great. I verified that the clutch position sensor plug wires are the green and orange ones like others stated on here. I unplugged the MAF plug and it made no difference however it probably wouldn’t because I haven’t plumbed in the intercooler piping. The throttle body is opening and closing when I press the gas pedal. This is a brand new motor from ATK performance. All new sensors. Donor car started great and ran fine. Let me know if anyone has any ideas.
 
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OptimizePrime

Well-Known Member
Check your battery - these cars are very sensitive to voltages

Does your VATS light go away? What you're describing sounds awful close to vats

Do you get an obd2 reading and your RPD turns on (if you have one) ?

Also, did you prime the fuel pump? If not, you may just need to crank it a few times
 

dastrups

Well-Known Member
So something is messed up with my OBD2 port because it will not connect to an OBD2 scanner tool and I have tried two different types to verify. The car had a Viper security system put on by the previous owner and the green wire to the OBD2 port was cut. I soldered in a green wire and ran it back to the big cluster of green wires that were soldered together. Would this potentially be the cause to the OBD2 port not working and can the OBD2 port not working be a cause for the car not starting? Car started and ran fine before taking apart the donor. Also dumb question but does the key fob TPMS need to be plugged in and where? Also there is a second picture with a plug by the BCM that I have no idea where it goes to.

Voltage of battery is 12.07 so not amazing but should be enough to crank, right? Voltage doesn’t drop by much when I go to crank.

VATS light does not stay on.

Fuel pump and throttle body butterfly valve work great. Primed the fuel pump many times now. Fuel pressure seems to be fine when I check it at the little fuel line valve.

When I go to crank and I hear a click it is coming from a relay on the BCM.

Also I deleted power steering so I don’t know if not having those plugged in would present an issue.
 

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Ross

Goblin Guru
The dark green wire should go to the OBDII port on pin 1, as well as the instrument cluster and BCM.
My LSJ has a dark green on pin 2 that only goes to the PCM, but it sounds like it is an LSJ only feature, so your LNF probably doesn't have this.
Pin 16 should have 12v, as long as the 15A fuse for the lighter is good.
Did you do your own wiring harness? The GM high speed LAN wires are suppose to bounce from the PCM to the BCM to the power steering to the OBDII port. When we removed the SRS module and the satellite radio modules, we were suppose to reconnect the GM high speed wires.

I wonder if your car will start if you were to turn the key on, then connect 12v to the purple wire on the starter? When my car has lost connectivity on the GM high speed LAN, I can get it to start this way... I extended the purple wire into the cabin, so I can jump the starter.

The TPMS plug goes to the TPMS module, which is a black plastic box, a little smaller than a pack of cards. I have mine plugged in, but am not sure it is needed. Of course the key fob and tire pressure sensors won't work without it.
24469
 

Rabid Sloth Racing

Active Member
Was your key all the way on when you jumped the starter? If it wasn't the car will cut off as soon as you stop jumping the starter.

I have an issue that I can't track down where the car won't start from the key. After checking the grounds then cleaning and sealing all the connectors it was still intermittent. Apparently the BCM's really don't like humidity or dust and we should be sealing them. Following the lead from others on here, I wired up a push button switch to the purple wire on the starter on one side and a fused link to the battery on the other.
 

OptimizePrime

Well-Known Member
You don't need to have the purple plug plugged in since you're manual steering. The other one looks like the plug that goes into the little white box that sits next to the BCM (I'll edit it with specifics later). Yea your voltage is quite low, put her on a trickle.

If I'm a betting man, your obd2 issue (and probably your starting issue) is because you didn't connect the wires shown in this post.

more info
 

dastrups

Well-Known Member
The dark green wire should go to the OBDII port on pin 1, as well as the instrument cluster and BCM.
My LSJ has a dark green on pin 2 that only goes to the PCM, but it sounds like it is an LSJ only feature, so your LNF probably doesn't have this.
Pin 16 should have 12v, as long as the 15A fuse for the lighter is good.
Did you do your own wiring harness? The GM high speed LAN wires are suppose to bounce from the PCM to the BCM to the power steering to the OBDII port. When we removed the SRS module and the satellite radio modules, we were suppose to reconnect the GM high speed wires.

I wonder if your car will start if you were to turn the key on, then connect 12v to the purple wire on the starter? When my car has lost connectivity on the GM high speed LAN, I can get it to start this way... I extended the purple wire into the cabin, so I can jump the starter.

The TPMS plug goes to the TPMS module, which is a black plastic box, a little smaller than a pack of cards. I have mine plugged in, but am not sure it is needed. Of course the key fob and tire pressure sensors won't work without it.
View attachment 24469
How can I go about hooking up 12v to the purple starter wire. Jumper cables?
 

dastrups

Well-Known Member
You don't need to have the purple plug plugged in since you're manual steering. The other one looks like the plug that goes into the little white box that sits next to the BCM (I'll edit it with specifics later). Yea your voltage is quite low, put her on a trickle.

If I'm a betting man, your obd2 issue (and probably your starting issue) is because you didn't connect the wires shown in this post.

more info
I’m going to look into this. Seems like they are definitely related issues.
 

Ross

Goblin Guru
How can I go about hooking up 12v to the purple starter wire. Jumper cables?
The battery 12V wire is the top of my starter motor... so if I were to use a wire or screwdriver to connect along the red line, it would energize the little purple wire on the starter, should be able to click the solenoid, and start cranking the engine. If the key is on, it should start the engine.

If you want to bypass the solenoid, you could run a screwdriver vertically, (connect the 2 big posts) and it will energize the starter motor directly. Expect a big spark, as you are running 100+ amps thru your screwdriver. The other method only draws a small amperage thru the jumper wire, as the solenoid will handle the high amperage starter motor.

24477
 

dastrups

Well-Known Member
Was your key all the way on when you jumped the starter? If it wasn't the car will cut off as soon as you stop jumping the starter.

I have an issue that I can't track down where the car won't start from the key. After checking the grounds then cleaning and sealing all the connectors it was still intermittent. Apparently the BCM's really don't like humidity or dust and we should be sealing them. Following the lead from others on here, I wired up a push button switch to the purple wire on the starter on one side and a fused link to the battery on the other.
Do you mean like literally turning the key to start it or just all the way to the on position right before you make the final turn to start it? I feel like I’m overthinking this.
 

Ross

Goblin Guru
If your engine won't start when the key is turned to the start position,
then leave the key in the on position,
and energize the purple wire on the starter. This bypasses the clutch safety, and the high speed data communication issues, and will crank the engine.
 

dastrups

Well-Known Member
The battery 12V wire is the top of my starter motor... so if I were to use a wire or screwdriver to connect along the red line, it would energize the little purple wire on the starter, should be able to click the solenoid, and start cranking the engine. If the key is on, it should start the engine.

If you want to bypass the solenoid, you could run a screwdriver vertically, (connect the 2 big posts) and it will energize the starter motor directly. Expect a big spark, as you are running 100+ amps thru your screwdriver. The other method only draws a small amperage thru the jumper wire, as the solenoid will handle the high amperage starter motor.

View attachment 24477
If your engine won't start when the key is turned to the start position,
then leave the key in the on position,
and energize the purple wire on the starter. This bypasses the clutch safety, and the high speed data communication issues, and will crank the engine.
I guess my starter solenoid posts look a little different. Only two posts. I did jump the starter with a paperclip on pins 87 and 30 on the crank relay and it turns over great. It tries for a second to fire up and then dies immediately. Not sure if it’s because a vacuum issue with my intercooler not being plumbed in yet. I did try disconnecting the MAF plug and I did run the fuel pump enough times that I feel it’s not air in the line. Still no crank with the key. I do get 12V at the pin 16 on the OBD2. I was going to try optimize
You don't need to have the purple plug plugged in since you're manual steering. The other one looks like the plug that goes into the little white box that sits next to the BCM (I'll edit it with specifics later). Yea your voltage is quite low, put her on a trickle.

If I'm a betting man, your obd2 issue (and probably your starting issue) is because you didn't connect the wires shown in this post.

more info
Are you referring to these two wires?
 

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dastrups

Well-Known Member
If your engine won't start when the key is turned to the start position,
then leave the key in the on position,
and energize the purple wire on the starter. This bypasses the clutch safety, and the high speed data communication issues, and will crank the engine.
My starter has one less post on the solenoid but perhaps the plug is essentially the third post. I have jumped the starter with the paperclip on pins 87 and 30 of the crank relay and it turns over great. Tries to fire up but then dies immediately. Cycled the fuel pump several times so I don’t think there is air in the line. Unplugged the MAF since my intercooler plumbing isn’t hooked up. I didn’t have the power steering or RPD plugged in last time I tried so I will try that this weekend. I also put a new battery in and put a trickle charger on. 12.49V. I also get 12.49V through pin 16 on the OBD2.
 

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Ross

Goblin Guru
The power steering and RPD need to be plugged in, in order to get the data signal to the OBDII port.
I'm thinking if you can get the codes pulled from the OBDII port, we will have some clues as to why the engine is not staying running.
 

dastrups

Well-Known Member
The power steering and RPD need to be plugged in, in order to get the data signal to the OBDII port.
I'm thinking if you can get the codes pulled from the OBDII port, we will have some clues as to why the engine is not staying running.
Oh I see. Hopefully it’s as easy as that. I will try this out tonight.
 

dastrups

Well-Known Member
"Unplugged the MAF since my intercooler plumbing isn’t hooked up."

Why?
Well I tried both plugged in and not plugged in. I saw on the forum people having issues with it not idling and when they unplugged it the problem went away.
 

dastrups

Well-Known Member
But that has nothing to do with the intercooler piping. Are you talking about air piping not being connected?
Ya the charge pipes from turbo to intercooler to throttle body. I only have the air intake setup. It may not have any effect. I just tried it hoping it would be that.
 
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