Electrical starting system shutdown-could be nuclear meltdown

[tomtom72]

I just had a BFO.....yea, I'm very senile. One of the things that the CCM does is house the VATS system. The VATS system is just an electronic switch or relay for the fuel pumps. That's what keeps the bad guys from hot wiring our cars. No key pellet ; no fuel. You hear the pumps right? Just humor me as an old guy who's senile.......Hook up a fuel pump pressure gauge to the rail. Drain off the built up pressure thru the dump, and then go put the key back in and turn it to run and observe the gauge. Sort of like the start of the fuel pump diagnostics KOEO test flow chart in section 6E. If you got F-pressure, the VATS & key & possibly key cylinder wire are all okay. I think that diagnostic thought train is valid.


Tom

[Dave2]

Further data:

Old trickle charger dead-no output though charge indicator is green

Purchase new trickle charger

Data from vehicle:

fuse keyoff key on* *new trickle charger connected
LCD 13.1v 12.6v
ECM 0v 12.7v
CCM 0v 12.5v

Data matches normal power side of CCM (service manual section 8A-50.8)
Looks like next step is get into the dash to check ground side resistance thru harness to ground. I contacted http://gmautocomputers.com/ who rebuilds the CCM and ECM's for their experience. I described my symptoms to the gentleman and he indicated it fit a CCM failure, and these units are susceptible to power spikes (16v+). (Avoid jumping vehicle with a battery booster). Possible power spike from old charger that failed took CCM with it since CCM is always powered up. Rebuilt cost $280, current 10 day turn around time. I'm still hoping for a ground side issue (get out of jail free card- though it's feeling more and more like a Hail Mary pass).

[Dynomite]

Originally Posted by Dave2

still had no interior lights, dash LED, no security indicator, or door chime. Headlight are nice and bright. Where should I start on diagnosing this?

Ground Connections as tomtom72 suggests.
There are two engine block ground connections (multiple grounds each) located just above the Bell Housing (rear of engine block) one on each side of the engine. There are several ground connections on the chassis near the battery frame rail and other ground connections near chassis components. There is also an engine to chassis ground strap from drivers side of engine block (on side rear of engine block) to drivers side frame rail. The main Battery negative cable attaches to the side of the engine block just in front of the Bell Housing (primarily for the starter ground).

Check for ground continuity of any suspect component using an ohm meter. With one probe on the negative battery terminal and the other probe on the negative terminal of the suspect component you should get zero ohms with ignition key off as most components are not grounded through any switch.

Loosening those two engine block connections will not be easy as I mistakenly left the HVAC fan ground disconnected when installing the engine last time from the passenger side engine ground connection. I tried to get at the passenger side block ground connection from underneath (It could be very difficult) and I have Headers which makes the underneath approach considerably different. Cleaning Engine Block Ground Connections

I decided to connect that HVAC fan ground to the rear most Plenum bolt instead which works perfectly as it helps keep that passenger side wire harness in place.

Disconnect ground wires, clean surfaces, clean grounding bolts or screws, use star washers if applicable.

As an aside.....and I am prolly the only one on this Forum......I do NOT use trickle chargers but rather disconnect negative battery connection if ZR-1, Toyota Truck, JD Tractor sits for a period of time without starting. When I reconnect the negative battery connection (even when sitting disconnected over winter) the ZR-1, Toyota Truck, JD Tractor fires right up. I do not have power leaking through all the ground connections or trickle chargers powered up with wires strung all over. Disconnecting a trickle charger takes longer than just reconnecting the negative battery connection.

In one of the photos below there is a Green Ground Wire to Chassis.
that Green Wire is the New Starter Relay Ground Wire Starter Relay, Wiring Harness, Battery, and Plugs Tricks

Ground Strap Connection to Engine.............................Ground Connection from Bat and Engine to Chassis
.................................................. ...................................(green wire is NEW starter Relay ground)



Ground Connections Bolt to Engine Pass Side....................Ground Connections Bolt to Engine Drivers Side


Torx #30 to remove Drivers side Batt Panel....................5/16 inch Flex Ratchet to remove Negative Batt Terminal
SS Allen Head Bat Hold Down bolt shown..........................I remove if ZR-1 left sitting for more than two days


Electrical Ground Connections and Clutch Start Switch Linkage

[scottfab]

Dave,
It would seem to me now that you've verified a good battery source that the next move is obvious. Rather than guess and do a hit-or miss approach why not just measure on one of the known faulty systems?

The courtesy lamps would seem a good choice. They are right there easy to get at. The goal is to determine if you missing ground or 12V at the lamp. From there you continue you hunt for the cause of one or the other, ground or 12v missing.

Steps:
1. take cover off one of the courtesy lamps.
2. remove bulb
3. place the black probe (important) right on the Neg post of the battery.
4. Measure inside the lamp socket on both contact points.
Either contact have 12V? If No then next step is to find out why so you can stop here. Next steps (not listed) would be 12V supply line troubleshooting.
5. If you have 12V on stop 4 then remove the probe on the Neg post of the battery and place the red probe directly on the Pos post of the battery.
6. Now probe the two lamp socket contacts with the black probe. Do you get 12V on one of the contacts? At this point if you get no 12V your missing the ground at the socket. Next step is ground fault isolation.

Since the courtesy lamp does not come on when you open the door you have to be missing ground or 12V (unless all bulbs are popped)
Let us know which one.........

[Dave2]

Ladies and Gentlemen- we have the answer........................

CCM failure. The failed unit that was in the car had a factory rebuilt sticker on it-
The DERM (SIR system) also had a factory rebuilt sticker
Sent my CCM unit to K&B Special Products Alpharetta Ga. (GM authorized rebuilder) 770-777-1034 and $280. The tech's there indicated #1 cause of failure is high voltage- either a spike or voltage regulator drift 15V+. But they reiterated several times that these units had a limited life, and have seen units just croak.
I reinstalled the rebuilt CCM in the car (remember the story of the proctologist who did a valve job on his car engine via the exhaust pipe,) the CCM is buried against the firewall so it's either a choice of pulling the whole dash or forcing it out the center console area and risk collateral damage. I voted for the former though it resulted in a lengthy delay due to my lack of free time.
Turned the key and everything worked!!!
Now I just need to figure out what to disconnect/bepass for the Low tire Pressure Warning system indicator- I'm not running the sensors in my street tires and rims.

See you at Carlisle!

[USAFPILOT]

I had similar symptoms after trying to jump start my car once. Turns out it was the Body Control Module that got zapped. Had to send it off for repair. It is a pita to reach, but can be done. A forum member here named "WeGone" helped me diagnose it. I should have a thread on here describing it in detail somewhere.

[XfireZ51]

Just pull the DIC and remove the bulb for LPT light.

[Dave2]

I like easy solutions. Have you heard of any problems by pulling the bulb for later (12 month+) when I show the car with the original rubber/transmittors?

[Schrade]

Did they tell you which circuits in the CCM had failed?

If I send a computer off to be TESTED, I want THEM to tell ME what is not working in my car, since they're testing each circuits' output and return signals...

[We Gone]

Originally Posted by USAFPILOT

I had similar symptoms after trying to jump start my car once. Turns out it was the Body Control Module that got zapped. Had to send it off for repair. It is a pita to reach, but can be done. A forum member here named "WeGone" helped me diagnose it. I should have a thread on here describing it in detail somewhere.

Was a while back, If I remember we used a spare CCM and a vats interrogate to bypass the vats to diagnose it.