No crank issue. 2010 Chevy Impala LTZ 3.9 litre.

First time here. Hope I can learn and increase my abilities. Have been involved with electronics for over 25 years. F4 Phantom jet electronic tech in the USMC for s few years in the eighties. Industrial mailing equipment tech for over 20 years. Extensive mechanical and electrical training. Love tackling challenging problems on vehicles. Here to increase my troubleshooting skills. Despise shotgunning parts trying to fix a problem Being able to diagnose a problem down to the direct issue is a learned thing that takes time. Especially with new vehicles that have complex electronics unlike the old point and condenser systems of yesteryear.

My issue. No crank on 2010 Chevy Impala LTZ 3.9. Have checked voltages and grounds on ECM. All 5 vdc references are present. All B+ voltages are present and all grounds are present. No communication to ECM or TCM from my cheap scanner. This all started with a replacement of the front right ABS sensor pigtail. In replacing the pigtail, I decided to replace the conduit on some of the wiring harnesses due to rotting, Removed the ECM & TCM from the air box to have better access to the main harness. Did not disconnect cables from the ECM or TCM. Removed connector from ABS module to ohm the wires from the ABS sensor to make sure there were no more opens before splicing in the new pigtail. Replaced pigtail, conduit, reinstalled the ECM & TCM Air box and components. Buttoned everything back up. Tried to start. Nothing. Noticed no gear selection indication or fuel gauge reading when key on. Fuel pump works. All relays are enabled that are required with key on. Have checked 5 vdc reference at several sensors. Checked good. Don't know where to go from here. Every signal I can check with a meter from the printed schematics are present. to the ECM. ??? Help
Thanks for any direction.
PC

Welcome.

You can hear the fuel pump prime and the cluster lights up, but the PRND indicator doesn’t show anything?

With the key out of the ignition and all doors closed, what is the resistance between pins 6 and 14 at the DLC? We want 60 ohms. 120 represents an open in the network. Zero represents a shorted network or module issue. From the results here, we can choose a better diagnostic direction.

No offense meant here, but are you positive you got the EBCM (ABS module) connector reinstalled fully? :huh: That style of connector can be a pain to get fully seated. Depending on where the EBCM lives on the GMLAN, it might explain the no communication and no crank.

I think I did. You are correct. It's a difficult connector. So if the ABS module isn't plugged in correctly, that will cause a no crank? I will focus on that connector. Also, I have been reading up on the BCM. Looks like the ignition signal goes through the BCM. If the BCM is satisfied, it will send a signal to the ECM to initiate a start sequence. Is that signal a data signal? if so, can I hook up an Oscilloscope to it and see it? If so , do you know what it should look like? I have scoped data signals before and they look lieka bunch of squigly lines. I mentioned I have an ABS/Traction control icon illuminated that will not go off with the rest of the dash icons. Those two stay on after the others go out along with the Check Engine icon. I believe the Check Engine Icon should stay illuminated until the engine starts unless there is a code set in the key on position. Again, I will focus on the ABS module plug for now. As for the data link connector omh check, I checked across the resistor. I will perform a check again as you mentioned. The schematic shows a 120 ohm resistor in the ECM. I should read 120 across the resistor. I read 110. Probably within the +/- % of the resistor. However, I will check across the pins you suggested and see what I come up with. Thanks for the feed back. I will post my findings after I perform these checks.

Regards,

Correct. No indication as to what gear it's in. Also, no fuel gauge movement. with the key on.

Even in my limited experience, I’ve seen all kinds of craziness caused by Chevy BCM. Try disconnecting the battery. If that doesn’t fix it, I’d chase down the PCM no comm first

i am almost sure that the abs module can be unplugged and still the car would start.

I am sure you have done this but I would start with checking power to starter and checking power to the s terminal on the starter when someone is turning the key to the start position.

no power to s terminal then i would check at the start relay to confirm that it is the control side of the relay you are having problems with if you need direction from there i can help but pretty simple of course i have done it a thousand times lol so maybe not.

on the no comm issue are there any codes in the other modules and if so are there any that say they lost comm with ecm or tcm? I am just thinking lets make sure the no comm is connected to the no crank before chasing what could have nothing to do with no crank another thing i would do is look at all the fuses it could have just blown a fuse.

OK guys. Here is the deal. As was stated by PDM, the ABS module connector wasn't seated all the way. Thanks PDM. You the man. However, I ordered a pre programmed ECM from FS1. Everything I read on Alldata and Mitchel suggested the ECM due to all the reference signals,grounds and B+ voltage being present. I know, I'm a knucklehead for that one. As Paul Danner says, don't be a parts changer. Anyway, same issue with the other ECM. After reading the post on the ABS connector, I focused on that. After a few minutes of wrestling it slid in all the way. So I try to crank.No crank, but, I now have gear selection and fuel reading. Mind you I have the new ECM installed. I remove the new ECM and install the original. Now we have a start. Evidently the ABS module was causing the no communication and no start issue. I don't see how but that was the culprit. The ABS module not connected correctly. However, the ECM I ordered isn't a plug and play. Only when I reinstalled the original ECM did the car start and run. Question. Even though the new ECM is suppose to be pre programmed, would I need to reprogram the keys to the new ECM or is that only for a new BCM? All that being said, it was the ABS connector all the time. Write that down in your notes of things to remember. The ABS module on a 2010 Impala that isn't connected correctly will render you a no communication problem and a no start, no gear selection or fuel reading. Even though the ABS module doesn't control those things, it causes the stated errors from whatever module controls them. Probably the ECM or BCM. Many thanks to all who helped with this. PDM, If I ever cross paths with you, I owe you a steak dinner. Again, thanks to all.

See my reply to PDM. Evidently, on a 2010 Chevy Impala, the ABS not being connected properly will cause the issue I had. No crank, no gear selection or fuel reading.

See my reply to the fix to PDM. as to the resistance check on the data link, I checked across the resistor according to the schematics. In my experience in electronics, if you check a resistor in series, you should read the stated ohms of the resistor. The resistor is rated at 120 ohms. I read 110. That is within probably within the +/- % of the resistor. However, if the resistor is on a board, you could read a different resistance through other components. I didn't get to the point of checking across pins 6 & 14 as you suggested. That was my next step. However, I solved the issue before having to go any further. Again, see my reply to PDM as to what the issue was. Thanks for your input. All of you guys helped me fix a problem I created.

well great to hear that PC and fyi thanks for your service i tip my hat to you fine sir

PC wrote: OK guys. Here is the deal. As was stated by PDM, the ABS module connector wasn't seated all the way. Thanks PDM. You the man.

That was Tyler. ...Tyler the man.

Sorry about that Tyler. Got my replies mixed up. Anyway, If our paths ever cross, it is you whom I owe a steak dinner. Thanks a million. See the response as to the corrective action as the the fix for my inability to properly seat a connector.

Haha. Yeah, I wouldn’t have suspected the EBCM to cause a no start.

PC wrote: Sorry about that Tyler. Got my replies mixed up. Anyway, If our paths ever cross, it is you whom I owe a steak dinner.

Thanks! Very glad to hear your Impala is back to normal.

All that being said, it was the ABS connector all the time. Write that down in your notes of things to remember. The ABS module on a 2010 Impala that isn't connected correctly will render you a no communication problem and a no start, no gear selection or fuel reading. Even though the ABS module doesn't control those things, it causes the stated errors from whatever module controls them.

That'd be because of where the EBCM lives in relation to the ECM, TCM and ICM. The GM HSLAN (High Speed LAN) isn't a star configuration, but 'linear'. A break in the HSLAN (like an unplugged connector) will impact all modules after the break. I can't get my hands on a wiring diagram for this network, but I'm willing to bet the EBCM is upstream of the ECM on this network.

I didn't get to the point of checking across pins 6 & 14 as you suggested.

The value of that test was to confirm an open in the HSLAN. Even if the ECM shows the correct resistance, the total network resistance (with the other terminating resistor present) should still be 60 ohms. A reading of 120 ohms at the DLC would have spelled out an open in the network.

See the response as to the corrective action as the the fix for my inability to properly seat a connector.

If it helps at all, it's not just you. I had an '07 Saturn Outlook today with very similar symptoms. EBCM connector wasn't fully seated.

Tyler wrote: I can't get my hands on a wiring diagram for this network, but I'm willing to bet the EBCM is upstream of the ECM on this network.

You da man, Chad. I don't know how you get those diagrams to match up so well. I tried once, failed miserably. :lol:

As posted, all the modules must be in a series configuration. I don't have a block diagram to see how the data flows, but, as a break in a wire renders an open, the data interruption, due to the improperly seated connector, caused a break in the data comm. That makes sense as to the no start/no communication issue.