projectcop

Hi folks;
I have located a 200 amp alternator for my 98 C5 and was wondering what, if anything needs to be changed besides the size of the charge wire to make this work?
Is there anything else that needs to be upgraded?
Are there any problems that this could cause in the electrical system of the car?
I want to get it right the first time.
Any suggestions would be greatly appreciated.

ajrothm

You will likely get the charge fault code on the DIC. Also the alternator may not start charging because the ECU sends the signal to the alternator to start exciting the field. Some cars have this issue, some don't. There are ways around some of this stuff. I'd wait and see if it acts up before you worry too much. Just add a 8 ga charge wire with a 10-12 ga fusible link section from the alternator to the battery. You should be fine.

lionelhutz

The charge system fault may occur. If it happens then it can be fixed via tuning.

But, the PCM has no active turn-on or voltage control over the alternator. Any claims that it does are false.

projectcop

lionelhutz;
Thanks much for the reply. Can you explain why this system fault shows and why it needs to be fixed via tuning? Is there any other way to fix this?
Thanks

reath1

The easiest way to fix it is to purchase an alternator from DC Power. Plug and play with no codes and plenty of juice.

lionelhutz

The manuals only lists a PWM range and the time out before it records a charging system code. It doesn't list what causes the message on the DIC. The timeout is something like 8 seconds I believe and the DIC message can appear right after startup before 8 seconds of time. Still, I suspect the message occurs when the PWM feedback goes out of range and possibly that it happens on the DIC immediately vs the timeout before the code is stored.

The stock alternator has a soft turn-on regulator. You can watch how slowly the voltage increases when the engine starts. So, I suspect the message is caused by some aftermarket units that do not have a soft-start and basically jump to a high duty cycle until the voltage rises and the duty cycle drops again. The PCM is seeing the duty cycle go too high which triggers the charge fault message in the DIC.

As for the tuning, you can turn-off the L and/or F terminal monitoring in the OS settings. If I had access to an alternator that didn't work correctly then I'd try disabling each one to know which feedback causes the warning. I'd also scope the differences in timing on the L and F circuits to see what's going on.

Fundamentally, the Valeo has F and L terminals that do the same function as the same terminals on CS130, CS144 and a bunch of other alternators. You could just hook an indicator light between ignition power and the L terminal and the Valeo would still work even without any connection to the PCM.