Oil light flashing while battery light is on 97 VW Jetta

This is an awesome resource, never even knew this existed until today. I tried to search the FAQ and other forums but have not come across anything like I am experiencing.

The battery light stays on and the oil light blinks while the car is running.

What happens: On my 97 Jetta, the speedo works intermittenly, has been for a while. Today the tach(rpm) guage stopped working on the way to work. After that the battery light stays on and the oil pressure light blinks while the car is running. Checked oil and it was full at lunch time. Checked oil after work, still full, started the car, decided to chance it and drove home. The car ran fine---does anybody here have any ideas as to the problem, checked the repair manual but it does not have a section on tach;s.

Some friends suggested the following, please add your input:

Tach/electrical problem, ecu thinks the car is not running as its not reading anything from the tach.

Disconnect negative battery to clear code(only problem is i don;t have the radio unlock code)

Check fuel cap and ensure its tight

Add a fuel additive as the new diesel does not have enough sulfur

I am going to buy some additve and check the fuel cap tonight after dinner, any other solutions. Thanks in advance for your input.

Same thing happened to me these days. Flashind oil light and steady battery light on 93 Jetta (pretty dim though), intermittent for a 2-3 days. A couple of times went off by accelerating. Yesterday - no sign of it - thought it went away. Oil level good. Engine running great. While driving to work today it was on all the time and noticed my headlights are weak. Driving back home battery went dead - not even turn signals - the fuel valve cut the engine off a few times when idling but managed to start it again while the car was still moving. I suspect it's either a voltage regulator/ brushes issue, or a short in the oil pressure sensor circuit. Now I have to charge the battery first to see what actually happened.
Any idea if brushes are replaceable and where can I find them? Everywhere I checked they are only selling the voltage regulator ~125 +tax.
If anyone has any clue, please reply

low voltage will cause all sorts of problems, so get the battery and alternator checked. a voltage regulator with brushes built in in my area ( for a bosch alt) is about 55$, this is the most common failure on a bosch charging system

Voltage regulator in the alternator went bad. It is probably over charging get fixed asap. Just had one here at over 16 volts not good for electronics.

Confirmed -voltage regulator problem.
Replaced - all fine now

electrical problems

The fuel cap has Nothing to do with your problems!
Check and clean all grounds, especially those under your battery.
Sorry about not knowing your radio code but that battery will need to be replaced some day!

Consider one of those 9V gizmos from Wally World when you need to changeout the battery. I haven't used them, but it says you just plug it into the cig lighter socket and it keeps all your radio and other info intact while changing out the battery. Only a couple bucks.

[e battery light stays on and the oil light blinks while the car is running.

. Today the tach(rpm) guage stopped working on the way to work. After that the battery light stays on and the oil pressure light blinks while the car is running.

same happened to me (except for the alt light) , the wiring going from the alternator (w terminal) is what drives the signal to the tach . the oil light circuit is somehow tied in . in my case ,the problem was a broken wire (red/white?) from the alt to the tach . fixing the wire restored the tach and stopped the blinking .

Some friends suggested the following, please add your input:
Tach/electrical problem, ecu thinks the car is not running as its not reading anything from the tach.
Disconnect negative battery to clear code(only problem is i don;t have the radio unlock code)
Check fuel cap and ensure its tight
Add a fuel additive as the new diesel does not have enough sulfur

Click to expand...

my suggestion: get friends who actually know something about cars!