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i had the exact same symptoms, cranks but no start after motor install. I found the ground wiring (TAC Module) on the block above the starter G106 was damaged. This ground is also the negative for the battery. If you relocated the battery to rear, you may messed with this ground. Good Luck!
I pulled plugs they have fuel on them and smell fuel when cranking, fuel pump also primes when key on. Plugs are also new. Logging also shows each cylinder firing 1-8.
Has spark on both sides, all fuses have 12v both sides, including the ones during crank. Battery is new and on a tender with 12.5+ volts.
New parts:
Starter
Starter relay
Battery
Ignition switch
Crank Position sensor
Cam Position Sensor
Throttle Position Sensor
Spark Plugs
Wires
Tried other PCM
Tried other TAC module
Tried swapping relays
Tried running with MAF unplugged
I also have LCM5 installed, still get Service Column Lock, not sure if it's related but the LCM5 was supposed to eliminate that.
I do have a code B2809, the only thing I could find on that had to do with column lock so I guessing that code is just related to the LCM5
I've also tried a second BCM after doing the 30 min relearn and they both had a no start. They're both pre-owned BCM's so I don't have any history on them.
Originally Posted by Bill Curlee
There are several PCM specific fuses. Some are HOT at ALL TIMES and some are ignition switch powered.
Check each fuse and see if you have FULL BATTERY VOLTAGE on each fuse test slots.
On top of each fuse are two test slots. Test each test slot on the fuses with a DC Volt Meter to a good chassis ground.
Not sure I mentioned before MIL lamp is likely burnt out, I can log MIL on/off but never illuminates on the IPC, but it does report on when called on my scanner.
Originally Posted by rwobs777
Yes, he has fuel pressure he said but FIRST we have to know if he's getting spark !!...he tried the brake cleaner in the intake I think he mentioned...if he had spark it should have at least tried to start...isn't it great troubleshooting in front of a computer...LOL !!! p.s. No MIL LIGHT during start and dead panel cluster concerns me...wish I had a picoscope !!!
I pulled plugs they have fuel on them and smell fuel when cranking, fuel pump also primes when key on. Plugs are also new. Logging also shows each cylinder firing 1-8.
Has spark on both sides, all fuses have 12v both sides, including the ones during crank. Battery is new and on a tender with 12.5+ volts.
New parts:
Starter
Starter relay
Battery
Ignition switch
Crank Position sensor
Cam Position Sensor
Throttle Position Sensor
Spark Plugs
Wires
Tried other PCM
Tried other TAC module
Tried swapping relays
Tried running with MAF unplugged
I also have LCM5 installed, still get Service Column Lock, not sure if it's related but the LCM5 was supposed to eliminate that.
I do have a code B2809, the only thing I could find on that had to do with column lock so I guessing that code is just related to the LCM5
I've also tried a second BCM after doing the 30 min relearn and they both had a no start. They're both pre-owned BCM's so I don't have any history on them.
mmm???...THIS IS A GOOD ONE !!...ok, you have good spark, you have fuel (even if the fuel pump was weak you had said you tried starting with brake clean...it should have at least tried to start...I'd still check to see if you have a 5 volt ref. to either the ECT sensor brown wire) or TPS (green wire) on the engine...KEY ON and SENSOR UNPLUGGED...I'm just curious !!
I think its been mentioned a couple of times but its VERY IMPORTANT!
"robmiz" just said it again " I found the ground wiring (TAC Module) on the block above the starter G106 was damaged. This ground is also the negative for the battery. If you relocated the battery to rear, you may messed with this ground."
If that little wire isn't grounded,,, It will NOT run! I've seen people accidently attach it to the positive power terminal on the solenoid!
Locate that wire (ITS SHORT AND SHOULD BE ATTACHED TO THE SAME POINT ON THE BLOCK AS THE LARGE NEGATIVE GROUND WIRE ON THE BLOCK!)
Might be on to something, both TPS low ref green and yellow have 5v. ECT is 0v.
I pulled the PCM connector and the brown wire from C1 Pin 80 to the connector has continuity, but no 5V ref at the connector?
Originally Posted by rwobs777
mmm???...THIS IS A GOOD ONE !!...ok, you have good spark, you have fuel (even if the fuel pump was weak you had said you tried starting with brake clean...it should have at least tried to start...I'd still check to see if you have a 5 volt ref. to either the ECT sensor brown wire) or TPS (green wire) on the engine...KEY ON and SENSOR UNPLUGGED...I'm just curious !!
Hard to tell from this pic, there are two ground wires there, the engine ground, to chassis in my case and small ground wire which is the one I believe you guys had mentioned. They look to be in good shape.
Originally Posted by Bill Curlee
I think its been mentioned a couple of times but its VERY IMPORTANT!
"robmiz" just said it again " I found the ground wiring (TAC Module) on the block above the starter G106 was damaged. This ground is also the negative for the battery. If you relocated the battery to rear, you may messed with this ground."
If that little wire isn't grounded,,, It will NOT run! I've seen people accidently attach it to the positive power terminal on the solenoid!
Locate that wire (ITS SHORT AND SHOULD BE ATTACHED TO THE SAME POINT ON THE BLOCK AS THE LARGE NEGATIVE GROUND WIRE ON THE BLOCK!)
See if you have 5 volt ref. at pin 48 at PCM which is a gray wire that goes to the MAP sensor...all GM's use this 5 volt ref. at "sensors"....MAP,MAF,ECT,TPS etc !!...I'm assuming you have a wiring schematic !!...making progress !!
Just for the sake of checking,,, Pull a couple of plugs from each bank and make sure that you have compression. I KNOW it sounds dumb, but it seems to be turning over very fast.
So you say you have FUEL PRESSURE. Is it actually spraying out the injectors???????? When you pull the plugs examine them and if its not starting, it/they should be wet or smell of fuel.
Spark. Actually check the spark on each bank. See what it looks like. Should be nice blue spark and able to jump a good pug gap
If you have fuel, spark and compression, it should RUN!
RECHARGE the battery!! 8 VDC during cranking is VERY VERY LOW!! The module low voltage cut off is around 8 VDC!!
Bill
Yes , my car died mid race cranked the same. Turned out to have broken the timing chain.
I do have +5v at the Map sensor gray wire Pin 48 from PCM, gonna triple check ECT for 5v ref.
Originally Posted by rwobs777
See if you have 5 volt ref. at pin 48 at PCM which is a gray wire that goes to the MAP sensor...all GM's use this 5 volt ref. at "sensors"....MAP,MAF,ECT,TPS etc !!...I'm assuming you have a wiring schematic !!...making progress !!
I double checked, no 5V on the brown wire at the ECT. From this diagram I believe the brown wire is ground ref not a 5v ref. Where as the Gray wire on the MAP is a 5v ref, which I have at the MAP and TPS.
Originally Posted by busta
I do have +5v at the Map sensor gray wire Pin 48 from PCM, gonna triple check ECT for 5v ref.
You have 5 volt ref. on at least 2 sensors so I think we are ok..If one of those 5 volt ref. wires were shorted to ground it would drag them all down !!!...I was watching your video again...sounds a little "off" while cranking...not a consistent crank from what I can hear...sounds like a compression test is maybe in order...too bad you couldn't do a relative compression test...much faster...amp clamp on your positive battery terminal to starter...one or two cranks and your done !!....and if you have a vacuum gauge you can check the vacuum while cranking...3-5 inches Hg normal....wish you didn't have to change all those parts...it will get fixed !!
You have 5 volt ref. on at least 2 sensors so I think we are ok..If one of those 5 volt ref. wires were shorted to ground it would drag them all down !!!...I was watching your video again...sounds a little "off" while cranking...not a consistent crank from what I can hear...sounds like a compression test is maybe in order...too bad you couldn't do a relative compression test...much faster...amp clamp on your positive battery terminal to starter...one or two cranks and your done !!....and if you have a vacuum gauge you can check the vacuum while cranking...3-5 inches Hg normal....wish you didn't have to change all those parts...it will get fixed !!
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"!!!...I was watching your video again...sounds a little "off" while cranking...not a consistent crank from what I can hear...sounds like a compression test is maybe in order..."
I would verify the tac module connector pin 15 is grounding out... if you haven’t done so. Also as a watch out, cranking the motor over and dumping fuel repeatedly will wash out the cylinders and contaminate the oil with fuel.
I would verify the tac module connector pin 15 is grounding out... if you haven’t done so. Also as a watch out, cranking the motor over and dumping fuel repeatedly will wash out the cylinders and contaminate the oil with fuel.
I have a ground at pin 15, as a precaution I just replaced oil and filter since it did have a good amount of fuel in the oil.
I also pulled both tanks emptied and refilled with fresh gas, old gas was discolored and not fresh.
I pulled the inj fuses and disconnected fuel pump, cranked engine to build up oil pressure and put it back together still has same symptom
On my log I see that TP is at 16% from what I read it should be looking for 0%? I'm not sure what would cause that or if it's related to the not starting. I did try a new TPS sensor still says 16%.
Our throttle blade position is NEVER ZERO. We do not have an Idle Air Control Motor (IAC) so the PCM sets the throttle blade to open XXX degrees to allow for engine idle. It uses the last known good idle blade angle to set the blade opening.
Another TPS check. With the ignition in the ON position, you can monitor using VCM scanner or visually the throttle body blade position by pressing the gas pedal. You should able to hear the motor/actuator moving.
You have fuel and if TPS is functioning correctly air...but no spark. I would check the ignition ground G107 on the rear driver side cylinder head. I would also check the braided ground strap on the driver side of the block. Both of these not properly grounded will have similar no start condition.
04-18-2018, 06:39 PM
Easy to pop off a valve cover and see if there's valve action during cranking..
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