993 Faq Frequently Asked Questions about the Porsche 1994-1997 993


993 3rd Brake Light fix

Filed under: Electrical System,Lighting — Jeff 993TT @ 10:59 pm

Want to replace those broken bulbs in your 993 3rd brake light ? Follow this DIY

3rd brake light DIY


Upgrading the Turbo S scoop positioning lights

Filed under: Electrical System,Exterior,Lighting — Jeff 993TT @ 10:40 am

The front fog lights can be replaced with the Turbo S air scoops. These provide additional cooling for the AC condenser and oil cooler.

However, the Turbo S air scoops do not provide the same output as the existing fog lights. This is becuase the lights are considered to be “positioning” lights and not actual fog lights. The wattage of the positioning lights is only 4W. Many people have upgraded to a 10W bulb for a minor upgrade in brightness.

A more effective option is to replace the bulb with actual driving lamps. A drop in replacement for the existing positioning light is the PIAA 002X 35W Extreme White Driving Lamp. The fitment is perfect and the light is easily secured using the provided double stick tape. The PIAA lights are about $104 and are available from autosupermart.com. Installation time takes about 1 hour and the existing foglight wiring can be used.

Here are some photos of the stock and PIAA upgraded Turbo S scoops: Turbo S foglight replacment



Why is the ignition key to the left of the steering wheel?

Filed under: Electrical System,General — Jeff 993TT @ 10:00 am

The ignition switch on the left side of the steering wheel ( right side for RHD cars ) is left over from Porsche racing heritage.

These old races started with the drivers sprinting to their cars, starting the car, and then driving away.

Porsche put the ignition on the left side to make it faster for the driver, allowing the driver to start the car and shift into gear at the same time.



Replacement battery

Filed under: Electrical System — Jeff 993TT @ 5:55 pm

The factory battery only had a service life from 3 to 5 years.

Any replacement battery of group size 48 will work. You will need to get the version with the vent tube. The vent tube is designed to vent gasses produced during charging. Failure to connect the vent tube may result in a hazardous build up of gasses in the luggage compartment.

Popular brands are: Interstate, Sears, etc.

Many 993 owners prefer using sealed maintaince free batteries over the traditional lead/acid batteries mentioned above. The advantages are:

a) Completely sealed and truly maintenance free
b) Dry cell technology, so no risk of acid leakage and subsequent corrosion (commonly seen with traditional batteries)
c) Vent tube is not needed.

Popular drop in replacement brands are the Exide Orbital Select and the Optima Red Top.

The Red Top can be ordered from BatteryWeb.com. The model number is 75/35-925. Since these batteries are sealed, they can be shipped via normal means, ie USPS, UPS, etc with no restrictions.

A downside to these sealed batteries is that have a higher internal resistence than lead/acid batteries if fully drained. You may need to bring the battery to an auto parts store to have them charge it with their high power chargers. Most auto parts stores offer complementary battery charging.

Note: You will have to reprogram your factory stereo with the appropriate radio codes after you have reconnected your new battery. Click here for more information.

Note: If the battery is disconnected, the data for the engine electronics stored in the control unit will be erased. When the battery is reconnected, the engine must be run for approx. 10 minutes to allow the control unit to re-acquire this data. During this period, the engine may idle unevenly or too fast.


How to change out the ECU

Filed under: Do It Yourself (DIY),Electrical System,Engine — Jeff 993TT @ 5:42 pm

The ECU in the 993 is under the driver’s seat.

To remove the driver’s seat, follow these instructions: How to remove the front seats

After you have the seat removed, you will see a metal cover over the ECU. These bolts are “blind” bolts. That means that these bolts don’t have a bolt head you can use a tool to unscrew them. Use a dremel tool to square off the bolts and then remove them using pliers.

After you have removed these blind bolts, replace them with regular bolts that you can use a rachet set on.

After you remove the metal cover, you will see the ECU and can remove it.


What is a DME relay and why should I carry a spare?

Filed under: Electrical System — Jeff 993TT @ 9:50 am

Starting problems may be linked to a faulty relay used for the fuel pump.

Porsche used a relay with a 944. part # prefix well into the 993 run, and later replaced that part with part # 993.615.227.00.

The 944 prefix relay was found to be faulty. Symptoms are the car cranks, but does not start.

As a precautionary measure, many owners have replaced the 944 prefix relay or carry a spare relay.

At $15, its cheap insurance.


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