Dead Bank
07-17-2018, 09:57 AM
#1
Dead Bank Long story short, all my driver side injectors are dead. Shut em off 1 by 1 with HP tuners, nada. Unplugged all of em at once, nada. Unplug 1 passenger side, engine begins to die.
I would think each injector has its own pin at the PCM to tell it to fire, right? My though its the first thing i should check is continuity in the harness from PCM plug to each of the dead injector plugs. Thinking there is a slim chance the cause of my problem is 4 broken wires in the harness.
Is there something else, other than a shot PCM, that would cause this? A ground for that bank i could have missed during the swap? fuse popped?
I would think each injector has its own pin at the PCM to tell it to fire, right? My though its the first thing i should check is continuity in the harness from PCM plug to each of the dead injector plugs. Thinking there is a slim chance the cause of my problem is 4 broken wires in the harness.
Is there something else, other than a shot PCM, that would cause this? A ground for that bank i could have missed during the swap? fuse popped?
07-17-2018, 10:46 AM
#2
TECH Senior Member
Unless you have done so, check EVERY ground in the system. It would surprise you how often that is the culprit.
07-17-2018, 11:02 AM
#3
Each of the injectors has it's own PCM controlled ground, however each bank shares a single ignition power feed. I would check your INJ1 or INJ2 fuse in the fuse block under the hood. Also check the two grounds that bolt to the back of the passenger side cylinder head to make sure they are secure.
07-17-2018, 11:29 AM
#4
Each of the injectors has it's own PCM controlled ground, however each bank shares a single ignition power feed. I would check your INJ1 or INJ2 fuse in the fuse block under the hood. Also check the two grounds that bolt to the back of the passenger side cylinder head to make sure they are secure.
Last edited by micbegz28; 07-17-2018 at 12:00 PM.
07-17-2018, 03:49 PM
#6
If both INJ fuses are getting good power, then I suggest you check your grounds. Also, a quick test you can perform is to swap the coil packs from bank to bank and see if the problem follows. If it does, then you have an issue with the coil pack itself, likely the harness.
Last edited by ss.slp.ls1; 07-18-2018 at 12:29 AM.
07-17-2018, 04:24 PM
#7
The INJ1/2 fuses are fed ignition power and will show 12v when keyed on. Remove the fuses and check for power with the key on with a multimeter. With one probe connected to a ground, touch the other probe to one of the tangs for the INJ fuse. If you don't get power touch the other tang (I don't know which one is the feed side). If you don't get 12v when touching either side, then you have a problem.
If both INJ fuses are getting good power, then I suggest you check your grounds. Also, a quick test you can perform is to swap the coil packs from bank to bank and see if the problem follows. If it does, then you have an issue with the coil pack itself, likely the harness.
If both INJ fuses are getting good power, then I suggest you check your grounds. Also, a quick test you can perform is to swap the coil packs from bank to bank and see if the problem follows. If it does, then you have an issue with the coil pack itself, likely the harness.
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07-17-2018, 06:08 PM
#8
TECH Addict
The ECU switches the grounds to trigger, so for the injectors, only power matters, ground is ALL through the ECU.
Check for 12V at each injector, check of pinch points in the harness, if I recall the early 4.8 and 5.3 trucks had
a issue where the harness rubbed on a hose or bracket and would break wires..
SOME Systems get the 12V via a buss in the ECU and its possible to have the power fail on a subset of the connections,
(Not sure if any LS motors do this,,, ) But Its a problem on
my Jeep which uses a lot of GM and FORD parts for injection and ignition..
The bad thing depending on the ecu build model/year/age/phase of the moon, the ground trigger circuitry in the ECU can have 1/2/4/8 chips, if you have the 2 chip version and one chip dies you lose one bank, 4 chip loses 2 cylinders per dead chip, 8 loses 1 injector per chip.. Just depends on the trigger circuitry.. The upside is those chips are replaceable if your a good tech, or you can send the ecu for repair if its a rare one.. Again haven't dissected a LS ECU to that level but its common in everything else..
Check for 12V at each injector, check of pinch points in the harness, if I recall the early 4.8 and 5.3 trucks had
a issue where the harness rubbed on a hose or bracket and would break wires..
SOME Systems get the 12V via a buss in the ECU and its possible to have the power fail on a subset of the connections,
(Not sure if any LS motors do this,,, ) But Its a problem on
my Jeep which uses a lot of GM and FORD parts for injection and ignition..
The bad thing depending on the ecu build model/year/age/phase of the moon, the ground trigger circuitry in the ECU can have 1/2/4/8 chips, if you have the 2 chip version and one chip dies you lose one bank, 4 chip loses 2 cylinders per dead chip, 8 loses 1 injector per chip.. Just depends on the trigger circuitry.. The upside is those chips are replaceable if your a good tech, or you can send the ecu for repair if its a rare one.. Again haven't dissected a LS ECU to that level but its common in everything else..
07-18-2018, 07:30 AM
#9
How can i go about checking for power at the injector without a noid light? Pull the plug and crank it with an ohm meter on it? Or do the injectors see constant power with key on and PCM grounds it to complete circuit when it is time to fire?
1. Last night after double checking the fuses for INJ1 and INJ2, i verified that the fuse itself was getting power, and it was.
2. After that, i pulled the PCM and checked for continuity between PCM pin and injector connector pin, all 8 are good.
1. Last night after double checking the fuses for INJ1 and INJ2, i verified that the fuse itself was getting power, and it was.
2. After that, i pulled the PCM and checked for continuity between PCM pin and injector connector pin, all 8 are good.
07-18-2018, 10:40 AM
#11
How can i go about checking for power at the injector without a noid light? Pull the plug and crank it with an ohm meter on it? Or do the injectors see constant power with key on and PCM grounds it to complete circuit when it is time to fire?
1. Last night after double checking the fuses for INJ1 and INJ2, i verified that the fuse itself was getting power, and it was.
2. After that, i pulled the PCM and checked for continuity between PCM pin and injector connector pin, all 8 are good.
1. Last night after double checking the fuses for INJ1 and INJ2, i verified that the fuse itself was getting power, and it was.
2. After that, i pulled the PCM and checked for continuity between PCM pin and injector connector pin, all 8 are good.
Have you tried swapping coil packs from bank to bank to see if the problem follows? I would also test for ignition power at both coil packs.
07-18-2018, 10:44 AM
#12
Disconnect the injector connectors. With the key on, you should have 12v at each connector. Should be a simple test since you already checked for continuity between the injectors and the PCM. The other wire of the injector connector that is not connected to the PCM should read the ignition voltage.
Have you tried swapping coil packs from bank to bank to see if the problem follows? I would also test for ignition power at both coil packs.
Have you tried swapping coil packs from bank to bank to see if the problem follows? I would also test for ignition power at both coil packs.
I didnt swap coils, but spark was verified on the failing bank. Should i still swap?
07-18-2018, 11:49 AM
#13
You should read 12v at the pink wire on each injector with the key on. The other wire from the PCM is only grounded by the PCM when that injector is commanded to pulse. If you are getting ignition power to all injectors and all coils on that bank then you either have a ground issue or a PCM issue.