7 OF 10

4 alternators have failed, twice now I had to replace ECU to regain regulation of alternator, or replacement alt. won't regulate.
After ECU swapped, re-programmed, re-licensed "HP tuner",
we're back on the road.
Initial failures were due to short to ground, subsequent ones due to above issue.Alt voltage drops 20 - 50 miles after short repaired and alt. replacement.
Fault on DIC is charge system failure, voltmeter drops to 10-9-8 V
Is there a way to regulate alternator external to ECU?
Will my driver info center [DIC] show "charge system failure "

lionelhutz

The PCM in a C5 never controlled the voltage or even turned-on the regulator. There is a lot of BS and misinformation floating around on this forum and the internet about how the charging system on a C5 works. All the PCM does is emulate an idiot light with an internal resistor and then monitor the terminals to ensure the alternator actually starts operating.

So, the stock alternator will operate stand-alone just fine. If you want to disconnect it from the PCM you could just put a light or resistor between 12V switched power and the L terminal on the alternator. Turn-off the L & F terminals in the system settings using HPtuners so the PCM no longer monitors those terminals or gives the charging system faults.

Of course, none of the above will fix the real issue you have which is either a bad connection or a run of bad alternators.

What was shorted to ground?

73Corvette

Bill Curlee

I agree

When you say SHOTED TO GROUND,,, most of the time people see the picture of SMOKE, FLAMES POPPED FUSES,, etc etc..

Sounds to me like the people that were doing your repairs doesn't understand how a C5 Charging system works..

If you can read a schematic,,, Here's one for your charging system:


EARLY 97-98 C5:





99-to 04

auctiondepot

[QUOTE=Bill Curlee;1589908693]I agree

When you say SHOTED TO GROUND,,, most of the time people see the picture of SMOKE, FLAMES POPPED FUSES,, etc etc..

Sounds to me like the people that were doing your repairs doesn't understand how a C5 Charging system works..

If you can read a schematic,,, Here's one for your charging system:



Im having the same issue from a short.
What has to be replaced,
Is it the fusible links that need to be replaced?
Where are these?

Thanks in advance.


I found the blown fusible link at the starter, had to remove the header to see it.

It is orange which I think is a 16ga or 12amp equivalent fuse.

http://www.stangnet.com/mustang-foru...erages.819889/

I think a Maxi fuse sounds like a better idea.

C5 Pete

Is it possible that a faulty alternator could cause the car to cut off at a high rpm?

For example, my car cuts off randomly at high rpm. It's as if I shut off the key and turned it back on. The dash goes dead, and it shuts off the scanner too. It's only for a moment, then it all comes back to life.

I'm checking all the grounds today and looking for a "smoking gun" of sorts... Hope I find it.

Thanks.

Bill Curlee

"Is it possible that a faulty alternator could cause the car to cut off at a high rpm?"


NO,,, But it sounds exactly like you are having an IGNITION SWITCH problem... Very common and easy to repair or replace. That would be the VERY FIRST place that I would look first!

I doubt that its a ground issue either.

Try the repair here:

- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

C5 Pete

Thanks Bill. I'll give it a shot.

Sorry for the hyjack.

7 OF 10

Latest short occurred when Davis GMC LEFT THE Positive battery cable loose.
Previous short was bad trailer wiring, shop used a 50 amp fuse to make problem worse.

7 OF 10

So the C5 is back at Davis GMC.
They diagnosed for 6 hours, want to install another gm alternator, but it has a clutch pulley, tech worries my 8 rib (a&a supercharger )won't swap.
I said hundreds of cars have this 8 rib pulley.
The car is a 6 spd manual, did they come with clutch pulley, or is that an automatic trans. Part.

7 OF 10

Latest short was a poorly installed fuse, 100 amp fuse between battery & fusebox.
Davis GMC zip stripped a plastic fuse holder to an A/C line, above the header.
Previously they left a battery cable loose. Original complaint was ABS light.
First short was another shop, BULLSEYE , who messed up trailer wiring, fused with a 50 amper, to make things melt.
So its back at Davis GMC . 6 hrs diagnosis later they found nothing, tried running 2 new wires from alt. To ECU.
Now they want to install a $450GM reman alternator, in place of the reman I supplied.
I offered to supply a used gm alternator i have in stock.
I hsve asked them to install light or resistor in ECU circuit as suggested.
Tx for the help. I need it with these Lethbridge Alberta shops.
IE : Leth. Peterbilt just did a CVIP inspection on my rig, replaced driveline center bearing , only hand tightened bolts, whole driveline hit the ground 500 meters down the road.

7 OF 10

Tx. Lionel, it was 3 different incidents of shorts to ground. Leaving my Vette down 16 months.
1 )Bullseye Customs installed Trlr .wiring wrong. I screwed up by plugging in & heading for the drags trip without checking therecwork. They also used a 50 amp fuse off the sub woofer on a 16 gauge trlr. live wire , I never requested...wait for it as, it gets worser.2) Davis GMC of Lethbridge Ab. Canada : left positive battery clamp loose, fried wire to melt starter solenoid. Car died 100 meters from there driveway, they refused to help push it back , I towed it in.
3)Davis blamed header heat, modified vehicle for #2 also indicated ECU must be swapped out as it acts as voltage reg. ( I now know better now tx. To this thread).Davis GMC, (at $125 / hr. )Used an amp kit to rewire, changed scheme to : Alt. to fusebox, to Solenoid but...messed up the job ; they created another melted wire by zip tying a clear plastic cased 100 amp fuse to the metal A/C LINE ! ABOVE THE HEADER, OUT OF SIGHT!
Replaced alt. # 5 Last month , left ecu alone, now all is well.
I