LS2 conversion,, engine will not start
On The Tree
Joined: Sep 2005
Posts: 103
Likes: 0
From: FLORIDA
If it is the fuel pump relay and nothing comes on . . it is something with the pump itself or the connection at the pump ( I would say not likely ).
If it does come on . . then find another relay . . maybe headlights or something . . and pull it out and put it in the fuel pump relay slot ( if it will plug in ! ) . . and then start the car up !
If you cant find another relay to fit it. . you will have to wait and go buy a new one.
I replaced the FP relay with the AC relay (same part number),,, turned the key, the fuel pump will not run, still no fuel pressure.
Then I checked the voltage between pins 85 and 86 with the key on, I have 1.00V.
I figure that the issue is not the relay. What else could be the root cause?
Do I need the oil pressure sending unit to do something before the fuel pump will come on?
Then I checked the voltage between pins 85 and 86 with the key on, I have 1.00V.
I figure that the issue is not the relay. What else could be the root cause?
Do I need the oil pressure sending unit to do something before the fuel pump will come on?
On The Tree
Joined: Sep 2005
Posts: 103
Likes: 0
From: FLORIDA
OK. . Pins 85 - 86 on the fuel pump relay will only have 12 v for about 3 - 4 seconds with the key on ! So you will have to have someone turn the key to check it !
Did jumping 87 - 30 turn the fuel pump on ?
Did jumping 87 - 30 turn the fuel pump on ?
Success! the fuel pump comes on with the key on and jumping across pins 87 & 30.
So, what does this mean to me?
Also, when I checked the voltage across 85 and 86, I used a digital voltmeter. I will have to do this again with an analog voltmeter and have someone turn the key for me. Thats for tomorrow.
So, what does this mean to me?
Also, when I checked the voltage across 85 and 86, I used a digital voltmeter. I will have to do this again with an analog voltmeter and have someone turn the key for me. Thats for tomorrow.
That means your pump is good. 
Technically, if you left 87 & 30 jumpered, you can crank the car and see if it'll run. That will mean the computer is functioning since it's firing the coils and opening the injectors, You do need to check 85 & 86 to make sure the relay is getting the 12V to energize. You can use a 12 volt test lamp too, in case you don't have a analog meter handy.
Technically, if you left 87 & 30 jumpered, you can crank the car and see if it'll run. That will mean the computer is functioning since it's firing the coils and opening the injectors, You do need to check 85 & 86 to make sure the relay is getting the 12V to energize. You can use a 12 volt test lamp too, in case you don't have a analog meter handy.
On The Tree
Joined: Sep 2005
Posts: 103
Likes: 0
From: FLORIDA
It mean you either have a bad relay. . . or your computer isnt functioning.
Testing the 85 - 86 when someone else turns on the key initially will tell you if you have a signal from the computer . . . . but remember . . it is only going to power for about 3 - 4 seconds. And it wont repower until the starter is turning over. . or the key is left off for 10 seconds (apxm). , and then turned back on.
If you get power across 85 - 86 . .the relay is bad.
If you dont get power . . the computer isnt sending a signal . . which means your computer isnt seeing the ignition on . . and Im not sure how your ignition is hooked to your computer. . . mine is just a little pink trigger wire.
Testing the 85 - 86 when someone else turns on the key initially will tell you if you have a signal from the computer . . . . but remember . . it is only going to power for about 3 - 4 seconds. And it wont repower until the starter is turning over. . or the key is left off for 10 seconds (apxm). , and then turned back on.
If you get power across 85 - 86 . .the relay is bad.
If you dont get power . . the computer isnt sending a signal . . which means your computer isnt seeing the ignition on . . and Im not sure how your ignition is hooked to your computer. . . mine is just a little pink trigger wire.
Thank you both.
I did try the AC relay in place of the FP relay. The fuel pump would not come on at key on. I doubt that both relays are bad, so I believe that the PCM is not commanding the FP relay to turn on. What would cause that? The PCM and all of the wiring, etc is still all factory stock. But since I pulled out my LS1 engine and replaced it with an LS2, maybe I did not get all grounds completed or messed something up.
I will follow up with the 85/86 key on voltage check.
I do have the grounds at the back side of the drvs side cyl head. I think that there are two wires welded to one metal tab, and one ground wire welded to a second metal tab. Both metal tabs are grounds to the back of the head with the same bolt.
I have been searching for a lone unconnected wire or connector somewhere around the engine, but I have not identified any, as yet.
I did try the AC relay in place of the FP relay. The fuel pump would not come on at key on. I doubt that both relays are bad, so I believe that the PCM is not commanding the FP relay to turn on. What would cause that? The PCM and all of the wiring, etc is still all factory stock. But since I pulled out my LS1 engine and replaced it with an LS2, maybe I did not get all grounds completed or messed something up.
I will follow up with the 85/86 key on voltage check.
I do have the grounds at the back side of the drvs side cyl head. I think that there are two wires welded to one metal tab, and one ground wire welded to a second metal tab. Both metal tabs are grounds to the back of the head with the same bolt.
I have been searching for a lone unconnected wire or connector somewhere around the engine, but I have not identified any, as yet.
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Verdad Gallardo So, the relay is good then.
Check pin 85 and 86. You can do three checks.
1. Pin 85 and 86, turn on the key.
2. Pin 85 and ground to the battery negative terminal, turn on the key.
3. Pin 86 and ground to the battery negative terminal, turn on the key.
The first test will probably yield nothing. The second two tests will determine which is bad, the 12 volt or the ground. I'm not sure which one is the positive side of the coil. If you do test 2 and 3 and get nothing, the computer isn't feeding the 12 V signal to the relay.
If you do test 2 and 3 and get something on one of the terminals, that terminal is the 12 volt feed, and the other terminal is ground for the relay coil and you have a bad ground.
Check pin 85 and 86. You can do three checks.
1. Pin 85 and 86, turn on the key.
2. Pin 85 and ground to the battery negative terminal, turn on the key.
3. Pin 86 and ground to the battery negative terminal, turn on the key.
The first test will probably yield nothing. The second two tests will determine which is bad, the 12 volt or the ground. I'm not sure which one is the positive side of the coil. If you do test 2 and 3 and get nothing, the computer isn't feeding the 12 V signal to the relay.
If you do test 2 and 3 and get something on one of the terminals, that terminal is the 12 volt feed, and the other terminal is ground for the relay coil and you have a bad ground.
I have no computer. I hot wired the fuel pump and I let the fuel pump run for about 5 seconds. I then got into the car and tried to start the engine, the engine turn over very well. but I have no spark and no fuel in the cylinders. So the PCM is not commanding the spark plugs or the fuel injectors.
Now what? How would I trace down this problem? I cant find any loose ground wires. The two or three on the back side of the drvrs haed is tight & secure. What would cause the PCM to behave this way?
Now what? How would I trace down this problem? I cant find any loose ground wires. The two or three on the back side of the drvrs haed is tight & secure. What would cause the PCM to behave this way?
Good suggestion. I will connect LS1Edit and attempt a 'READ PCM".
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"CONNECT FAILED" is my response from LS1Edit.
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"CONNECT FAILED" is my response from LS1Edit.
Last edited by Doc99SS; Mar 21, 2008 at 07:41 AM.
Well, you might want to pull the plugs off of it and check some of the 12 volt and ground pins to make sure that there isn't a bad connection. Just to give you an idea, I had G215 break on me which is that ground on the driver side cylinder head and it took a lot of feeling around before I figured out that the connection was in fact broken. There are five or six wires going to two or three clips. One of those feeds the PCM grounds.
Man, you are up late and up early!!!
I have not completely given up on my PCM. I will go back and check those grounds. As far as I can remember, there are only 3 ground wires bolted to the back side of the drivers cyl head. Two wires are welded to one metal tab, and one to a second tab.
It looks like there is a single dark brown wire coming out of the wiring loom that feeds the injectors on the drivers side. It comes out of the loom back near the firewall, then it goes over to the passenger side behind the intake and continues on. I loose the wire before it connects to anything, but I know that it is connected somewhere because I cant easily pull it out. What is this wire?
I have not completely given up on my PCM. I will go back and check those grounds. As far as I can remember, there are only 3 ground wires bolted to the back side of the drivers cyl head. Two wires are welded to one metal tab, and one to a second tab.
It looks like there is a single dark brown wire coming out of the wiring loom that feeds the injectors on the drivers side. It comes out of the loom back near the firewall, then it goes over to the passenger side behind the intake and continues on. I loose the wire before it connects to anything, but I know that it is connected somewhere because I cant easily pull it out. What is this wire?
I'm an insomniac. If I sleep 5 hours, I've had a good night. My father is the same way.
If it's a brown wire, it is one of the following wires:
C1-55 BRN EGR Pintle Position Sensor Signal
C1-70 BRN Low Oil Level Switch
C2-2 TCC Control Solenoid
C2-36 AIR Pump Relay Control
C2-60 BRN Ignition Control Reference Low Bank 1
C1 is the blue connector, C2 is red.
Given the location of the wire, it's probably C2-60, Ignition Control Reference Low Bank 1. I believe that goes to the coil packs on the driver side of the engine, which is run along with the injector wiring for the driver side. But even if that wasn't a good wire, you should still be able to connect into the PCM.
Check the following grounds in the ECU plug:
C1-1
C1-40
C2-1
C2-40
If you pull 12V from the battery, those should all register as good grounds. I'm not sure if you have to have all four grounded or if it is a common ground bus internally.
If it's a brown wire, it is one of the following wires:
C1-55 BRN EGR Pintle Position Sensor Signal
C1-70 BRN Low Oil Level Switch
C2-2 TCC Control Solenoid
C2-36 AIR Pump Relay Control
C2-60 BRN Ignition Control Reference Low Bank 1
C1 is the blue connector, C2 is red.
Given the location of the wire, it's probably C2-60, Ignition Control Reference Low Bank 1. I believe that goes to the coil packs on the driver side of the engine, which is run along with the injector wiring for the driver side. But even if that wasn't a good wire, you should still be able to connect into the PCM.
Check the following grounds in the ECU plug:
C1-1
C1-40
C2-1
C2-40
If you pull 12V from the battery, those should all register as good grounds. I'm not sure if you have to have all four grounded or if it is a common ground bus internally.
To be clear here, I want me to remove the two bolts that hold on the two main connectors to the PCM and check those pins with a Ohm meter for resistance from the pin to the shock tower (for example)? Or should I go from those pins (one at a time) to the positive terminal on the battery? I guess either should be a good confirm.
Oh yea, I dont know if you read the other thread, but I was able to upload and read off my LS2 tune. I checked several tables from the read file and they are intact & correct.
Oh yea, I dont know if you read the other thread, but I was able to upload and read off my LS2 tune. I checked several tables from the read file and they are intact & correct.
Yes, pull the connectors off the PCM.
If you are checking continuity, go from the terminal listed to the negative on the battery. Less chance of a faulty reading. You can also check them with voltage, your choice.
If you are checking continuity, go from the terminal listed to the negative on the battery. Less chance of a faulty reading. You can also check them with voltage, your choice.
Thank you.
OK, I have confirmed that that brown single wire goes to the oil pressure switch (or maybe its called the oil sending unit). Its a tall 1" OD sensor that screws vertically into the block behind the intake manifold.
OK, I have confirmed that that brown single wire goes to the oil pressure switch (or maybe its called the oil sending unit). Its a tall 1" OD sensor that screws vertically into the block behind the intake manifold.
Last edited by Doc99SS; Mar 21, 2008 at 03:22 PM.