Hey guys,
Having a problem with my car (99 manual car with an 02 EBCM(problem did not begin when the EBCM was replaced)) where every now and then (every 30s to 2mins) the engine sputters (dies if it's at low rpm) and the gauges (oil, coolant, tac, etc) spike and come back.
The grounds are good, most problematic ones are crimped.
I have a lot of "U" DIC codes and I'm thinking the PCM is the culprit because most modules show a U1016 and the PCM has no trouble codes.
Here's a list of the codes with the modules that show it:
1000 TCS, SDM
1016 TCS, BCM, IPC, SDM, LD, RD, RFA
1040 IPC, SDM,
1064 IPC, SDM, HVAC, LD, RD, RFA
1088 IPC
1096 BCM, SDM,HVAC, LD, RD, RFA
1160 HVAC
1176 IPC
1255 HVAC, LD, RD, RFA
1301 SDM

Any advice is welcome but I doubt it being the battery or the grounds.

 

I would suspect the ignition switch. One clue would be that it re starts OK, maybe on second or more tries.

 

It starts up immediately but dies again 30S after. It does it when idling or moving, so i don't think it's the ignition or grounds since it's not only if i hit a bump or something.
I'll swap the ignition switch later today (i bought one a while back trying to solve a different problem and it wasn't that, but I still have it. )

Keep the suggestions coming.

 

Any issues with the serial data line will sometimes manifest itself in a "start and stall" or a "no start" and especially with all those no comms you are experiencing. What happens is if a module (PCM, IPC) loses power or ground it will try it will "jump" on the data line trying to find a way "home" and cause all kinds of havoc...you'll see your gas gauge go to empty and the coolant temp max out

!!...you can find the 2 splice packs (pictured with both bus bars removed) near the BCM and remove the bus bar that connects all the serial data lines together and clean them with some emery cloth

 

 

Sorry, been busy with a new C5 I picked up last week.

Today I replaced the ignition switch, nothing changed.

Will clean the CAN splice again and see what happens.
Also got an ECU so I'll swap that to check it off the list.

 

It's probably NOT the PCM but I it's best to diagnose this issue with a voltmeter...don't know if you are good with electrical or even have a DVOM but you'll have to try and diagnose this while it doesn't start...if it doesn't start in your driveway we can let you know what to check...one area to check is inside the drivers door boot between the drivers door and the body...there is a connection inside if you peel back the boot so look for corrosion or pin fitment...if you truly believe it is the PCM I would check PCM powers and grounds !!...a good data line produces a 0-7 volt square with key on or engine running but you won't see this with a voltmeter...voltmeter is too slow and only shows "average" volts !!...you may see a little less than one volt...you can see if you have 12 volts or ground on any of those data line wires you had cleaned on both splice packs or "Star Connectors" as we call them !!

 

It was the ground splice next to the battery. I bent the pins and it's good now but i'll crimp it this weekend.

Thanks for the help.

 

Which ground splice are you speaking of ??...have a picture ??

 

Don't have a picture but it's the one in Bill's post (#6) in this link. Obviously mine looked clean and perfectly fresh since it's not my first rodeo cleaning the damn things. Oh freaking well. Crimping them does wonders.
https://www.corvetteforum.com/forums...re-report.html

 

Resuming this thread.
The problem is back. It happens way more rarely, but it still happens.
According to the manual, G106 (ground between battery and engine) grounds S120(the splice pack I mentioned being the problem) and S120 grounds 4 wires for the PCM.
The problem is S120 is now soldered and is definitely not the problem. G106 is clean and tight too. Ignition switch is replaced.
When I replaced the PCM, i was getting a security light and it would start and die immediately. Is there a need/procedure to teach it my key? I was under the impression that the key info sits in the BCM.

 

Unfortunately the PCM is not plug and play !!...it must be programmed with a Tech 2 or another high end scan tool that can do programming...if you have neither you can probably find a mobile tech who can do programming and who come by and do it !!!

 

Did you do the PCM BCM hand shake procedure?+

The PCM that you purchased should have been flashed if the place that you got it from was worth its weight in salt. But if it isn't you will have to have it flashed. I know someone that you can send it to if you cant find someone locally.

You can try to handshake the BCM/BCM using this procedure. Just make SURE that you have a good fully charged battery or put it on a charger for the time it take to do the procedure:

https://moduleexperts.com/gm-securit...arn-procedure/

 

So you guys think it could be the PCM? I got mine from LKQ, not sure if it's flashed but I can try to do the handshake.

Today i cleaned the ground near the passenger headlight and the one near the passenger door hinge and the splice under the passenger airbag.

No change.

 

Without doing some testing we can’t really tell you if the PCM is bad...the grounds behind the headlights aren’t really associated with what you’re seeing...what you really need to do is have it act up in your driveway and with the key ON see if you have 12 volts or ground on any of the serial data wires at the star connectors...a scan tool will tell you if you can communicate with any of the modules or can’t communicate at all !!..if you are not good with electrical you might find the diagnosis a little more difficult !!

 

i've wired entire cars before. This thing has been a royal pain.
So far I haven't gotten it to do it continously on the driveway. It goes off without me touching anything and comes back in 5-60 seconds without me touching anything. I'll measure the serial voltage next time to see what's what.

 

It's good you have an electrical background...the only thing I can suggest to eliminate a serial data bus issue is to backprobe the PURPLE data wire on either of the splice packs (Star Connectors) while you're driving and see if the voltage goes to 12 volts or to ground...with a voltmeter you'll see a varying .3 to .5 volts on a good data line !!...if you don't have back probes you can pick them up on Amazon for pretty cheap.

 

When my 02 ZO6 would go CRAZY, I would loose window control and the car would crank but not run. It drove me nuts till I discovered that the six pin door power connector was the culprit. I got stranded in a hotel parking lot while on a business trip. I opened the door to get some fresh air (cause the windows would not work) and everything started working correctly again.

I deducted that something in the door or door wiring was the issue. When it did it again, I opened the door and I SHOOK the wiring harness that runs through the rubber accordion tube between the door and body. PRESTO, Problem gone.

Popped the rubber accordion tube out and fished out the TWO door electrical connectors out of the hole in the door A pillar. There are two connectors. One is the SIX PIN POWER CONNECTOR! That is the one that gives the C5 these issues. The problem is caused by the female pins spreading apart and making poor contact with the male pins. This causes the door control module to turn ON and OFF, ON and OFF rapidly due to the **** poor connection and that causes the serial data buss to corrupt.

I bent the female pins so the little tong inside the female pin made solid contact with the male pin PROBLEM SOLVED!
To really determine if the female pins are damaged, you need a free male pin to do a male to female pin PUSH / PULL test to insure that the connection is tight between the two pins.

The other connector normally doesn't cause any issues. Different type of connector.

Just my experiences and 2 cents. If you look at the serial data buss with a scope, you would most likely see the corrupted data signal when the issue happens. Also when you pull up the DTC, you normally see a bunch of NO COMMS messages. Especially between the DCMs and BCM

 

I think you're right, Bill.
Today's findings: got it to freak out on the driveway.
Windows and door control don't work. ALL the modules are no comm.
Measured the voltage on both star connectors, 4.7isg VDC. disconnected the one with 4 wires, no change.
Opened the passenger door, closed it. Everything is good.
And now the star connector voltage fluctuates, as it should.

The 6 pin connector was serviced before and looks normal but to make sure it's the door, can I unplug both door connectors for a couple of days? Or disconnect its wire to the star connector?

 

If you removed the “bus bar” from Star Connector 2 and no change we can “assume” it is a module on the other Star Connector...the thing is that if the IPC on the other Star Connector doesn’t communicate with the door module the windows still will not operate...and yes, you can remove the bus bar for a few days and see what happens...if the issue returns the only way the car will start and run is to jump the PCM to BCM at Star Connector 1...those are the light and dark green wires...so you say a little over 4 volts on the data wire when you had the issue ??...the volt meter only averages the voltage and that data line is a very fast signal...I usually measure it on a 2 millisecond time base with my scope !!...good luck !!