I have a 98 , a4 Maggie blown ( non intercooled) modded with long tubes, blower cam, boost a pump, additional gages and alky injection. I harldy ever drive the car and I am one that will wash the engine bay ( I cant help it) I have never seemed to have issues with water or such as I am very careful.

However I do have two issues I cannot track down.

1. voltage. I have a new red top optima, alternator is working ( oem alt and voltage regulator)as far as I know, it shows good voltage cool. Car shows 14.1 volts on gage and dic, but when WARM it drops to 13.1.....I cant get to starter easily due to headers , but have loosened and tried to clean terminals there. I have also re-lugged drivers side frame mounted grounds ( by headlight) . Can someone lead me to why the voltage drops when warm. I have about .02 volts drop when reading at alt and battery so I feel connects are good.

2. My DIC controls switches lights went out after washing the car, it was ONLY the two lower , reset and whatever the one is above it. They are not blown as after the car set overnight they came back on. I assume its a water related issue from the washing. Where would I start to check connections for this issue??


The can has 26,000 miles , kept inside. no a daily driver and is very very clean. no plugged drains and never any leakage from battery.

HELP...where do I need to go on these issue.

 

1. Just a guess, but maybe the resistance through the ignition switch contacts is increasing as the car runs. The ignition switch is a fairly common failure item and the voltage reading on the DIC is measured after the ignition switch. If the battery is reading 14.1 when the DIC is reading 13.1 it would seem to point to the ignition switch as the possible cause.
here is a some info on troubleshooting ignition switch problems from Bill Curlee.
https://www.corvetteforum.com/forums...post1568186703

2. Don't know that answer, but if you have any aftermarket wiring from your mods running through the firewall in the area of the IPC make sure there is a drip loop in the wire and the hole is sealed.

 

When this happens, what is the voltage measured directly at the battery and at the alternator? Do you still have a .02v drop?

There is a lightbulb for every two adjacent buttons, so in your case there is just 1 lightbulb involved. Did you drive the car in between the lights going out and coming back on? I'm trying to see if perhaps vibrations and a bad contact might have something to do with it...

 

the drop is .02 when reading directly off alt. then going to battery, .02 drop. so thee is a little voltage drop. I guess it is one bulb , not two and I do have a brand new switch installed, I already thought that might be some voltage issue. where do I start with the connections on all the bigger stuff to check for corrosion. Its weird that one bulb went out and then came back on. but don't understand why voltage drops as car gets warm.

 

When the car is warm and you see the voltage down to 13v in the instrument panel, what is the voltage measured with a multimeter directly at the battery and at the alternator?

 

98 and 99 C5's are prone to voltage loss-----The most common issue is the electric driver's side seat adjuster-----It happened on my 98-----Once 1st started the seat adjuster would stay on all the time even if the key was off-----The battery would go dead or show low voltage after about 2-4 days-------I unplugged the pigtail under the driver's seat after setting it where I wanted and the battery never went dead again and always showed the correct voltage

 

I can't help you with your questions but I will give you a heads up on the Maggie which may or may not be relevant to your non intercooled setup. Be very careful with the water under the hood. My Maggied CTS V (intercooled LS6) had a problem with the knock sensors which, on my setup and most likely on yours too, are located under the supercharger. They are installed into some deep recesses in the valley cover that can and will fill up with water which leads to rusty/poor connections and you will then have to pull the supercharger to clean or replace the offending sensor/s. Just trying to help a brother out.