Our Community is 940,000 Strong. Join Us.


GM 2.4 sensor question for a mechanic


brocsbar
12-22-2010, 09:41 PM
1999 grand am 2.4 ....what sensors prevent the injectors from opening ?? Will not enuf pressure also not open them?

thephantom1492
12-23-2010, 01:48 AM
is the security light flashing?

brocsbar
12-23-2010, 09:22 AM
no flashing lights only a ucode u1040

thephantom1492
12-23-2010, 08:44 PM
U1040: Loss of Class 2 Communications with ABS

That could indicate a problem with the wiring, maybe the BCM can't send the password to the PCM, so it do not enable the injectors...

brocsbar
12-24-2010, 10:18 AM
or it could be the fuel pump and that code doesn't mean much right?

thephantom1492
12-24-2010, 10:43 AM
it could be the fuel pump.

But sure thing is that you have a serious issue with the abs, which mean it probably disabled, which mean that the car have a security feature that do not work, whick mean the car is not road legal right now.

brocsbar
12-24-2010, 11:33 AM
not worried about abs right now UNLESS it is stopping injecters from opening. I guess next week I'll put my otc injector cleaner in line with the fuel line and put the right psi to the rail and see if it starts and if it won't then I'll know the injectors aren't opening. I'll post back so everyone will know if this u-code will stop injectors from opening.

brocsbar
01-03-2011, 06:21 PM
just bypassed fuel pump with injector cleaner canister at 60 psi right after fuel filter. (With key on no fuel came out of pump) but that shouldn't matter as I was suppling the fuel right to the line.
did Ign module and plugs boots , cam and crank sensor and the fuel filter was clogged bad. But i don't see what is keeping it from opening the injectors. I have 12 v puling at injectors so r they just plugged that bad? that ecbm code is the only code i got. It will run for a second with a shot of ether so its got spark. I'm stumped? where is the modules? 1040 code is all it has?????

doctorhrdware
01-03-2011, 09:23 PM
U1040: Loss of Class 2 Communications with ABS

That could indicate a problem with the wiring, maybe the BCM can't send the password to the PCM, so it do not enable the injectors...

I agree with thephantom1492. This is how the system usually works.
The injectors will have +12Vdc always supplied to one side of the connection on the injectors. The other side of the connector which is the ground is controlled by the PCM. Since there is a communication issue, that would indicate that there is a wiring problem. I think that is why the injectors are not opening.

danielsatur
01-03-2011, 09:37 PM
There is a fuse for the injectors!

An ''Out of Car Injector Service'' is best.
Any diesel shop can micro bath, blowout, and test the flow rate.
A signal + clicking noise doesn't rule out a bad injector.

doctorhrdware
01-03-2011, 10:31 PM
If the fuse was blown, but then wouldn't the +12Vdc at the injectors be missing?

brocsbar
01-04-2011, 10:06 AM
good point plus i checked the fuses

brocsbar
01-04-2011, 10:11 AM
if the computer supplies ground to the injectors when all systems are a go, is it posible to wire up a ground for the injectors and bypass the computer sending ground? I still don't have fuel pressure though....i hate these cars

brocsbar
01-04-2011, 12:10 PM
when i turn the key to acc all the lights are on including security and then i try to start it and no flashing security(while starting), and when i stop trying to start and return the key to acc then there is no security light. is this normal? Also while it is trying to start the guages jump around all funny. but the car doesnt start then die it just doesn't start.......

brocsbar
01-04-2011, 12:45 PM
i don't think pump cause i supplied 60 psi to fuel rail with injector cleaner tool and still no start. Even blew out lines with air.....will start with starting fluid and die (but doesn't start and die with key just won;'t start)
I had a gr am 2.4 that would start and die right away and it was the airbag module under seat messing things up but this is a different animal it seems. No fuel pressure but still won't start when fuel supplied is what is stumping me. I will be here checking every hour for input or to answer ?s cause this mechanic is bound and determined to get to the bottom of this.

thephantom1492
01-04-2011, 05:07 PM
You have a class II communication failure, ground fault or power fault, or a mix of those.

But since you already have a class II communicatoin failure code... investigate it first. I'ld start by the airbag module, which is under the carpet, under the passenger side seat. If you forgot your window open and it rained, water could accumulate there and cause havok with the wiring. Some also reported damaged wiring due to where they ran the wires, that your passenger foot could have damaged

brocsbar
01-04-2011, 05:30 PM
will check that soon and post back i had that problem with a grand am b4 where it would start then die right away but this doesn't even start.

brocsbar
01-04-2011, 06:21 PM
disconnected airbag module and tried to start and NO GO! I guess ill try fuel pump but still can't understand why it wouldn't start with simulating fuel pump with my OTC injector pressurizer?

brocsbar
01-04-2011, 08:06 PM
It turned out to be the fuel pump but can someone tell me why it wouldn't run while using my otc injector cleaner 7448 with air hose attached sending 60 psi to the fuel rail. (as if i were cleaning the injectors). http://www.google.com/search?q=otc+7448&hl=en&prmd=ivns&source=univ&tbs=shop:1&tbo=u&ei=htEjTZ2SNtGcnweHt-D4DQ&sa=X&oi=product_result_group&ct=image&resnum=3&sqi=2&ved=0CEEQzAMwAg&biw=1024&bih=616

thephantom1492
01-04-2011, 08:40 PM
maybe there is a fuel pressure sensor somewhere... and you failed to provide the right pressure at the right time... beside that, I don't know...

brocsbar
01-07-2011, 11:33 AM
this is the first car this has done this to me out of about 100 and when cleaning injectors it is customary to totally disconnect the fuel pump power as to not overpressurize things and ruin pump. and with no shraeder valve one has to disconnect the line at fuel filter or rail to clean injectors....still not sure why??

Add your comment to this topic!