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Pelican Technical Article:

Control Board Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$300

Talent:

***

Tools:

Philips, Flathead screwdriver, 5mm Allen, 10mm socket, 13mm wrench

Applicable Models:

Porsche 993 Carrera (1995-98)
Porsche 993 Carrera 4 (1995-98)
Porsche 993 Carrera 4S (1996-98)
Porsche 993 Carrera S (1998)
Porsche 993 Targa (1996-98)
Porsche 993 Turbo (1996-97)

Parts Required:

Control board

Hot Tip:

Label things and take pictures

Performance Gain:

Working electrical system

Complementary Modification:

Get an extra DME relay

Let me state right up front that chasing down electrical problems is probably my least favorite thing to work on on a car and the Porsche 993 is no different. The 993's are known for electrical gremlins starting with the fact that the factory did a recall and replaced the entire wiring harness. If you are unaware if your 993 has had the harness replaced under warranty, call your local dealership with your VIN number and they will let you know. If it has not been done yet, it is a good idea to get the car in and have the factory replace the harness for free. The original harness dries out and cracks causing all kinds of potential problems.

The next area that 993s have problems with are the main control board; which is where all of the fuses and relays are located up in the trunk. These are known to actually go bad as well, but are not covered under a factory recall. If you are chasing down electrical problems, especially intermittent ones, try wiggling or pushing on the fuse. If this causes or fixes a problem, you need a new control board.

The board is not that expensive considering it is the main panel in a Porsche. It's actually pretty idiot proof to replace. Just take your time and take lots of pictures and when in doubt, label everything!

The main fuse/relay panel and control board is located under the hood in the front right side.
Figure 1

The main fuse/relay panel and control board is located under the hood in the front right side. Begin by opening the hood and unclipping the carpet to get access to the panel (red arrow).

With the carpet out of the way release the two clips (red arrows) and remove the lid.
Figure 2

With the carpet out of the way release the two clips (red arrows) and remove the lid.

If you are chasing electrical problems and pushing or wiggling a fuse causes or fixes a problem then you need a new control board.
Figure 3

If you are chasing electrical problems and pushing or wiggling a fuse causes or fixes a problem then you need a new control board.

Once you have identified that you are going to replace the board, do not go any further until you have disconnected the ground strap from the battery and placed it somewhere where it cannot accidentally come in contact with the post while you are working (red arrow).
Figure 4

Once you have identified that you are going to replace the board, do not go any further until you have disconnected the ground strap from the battery and placed it somewhere where it cannot accidentally come in contact with the post while you are working (red arrow).

To start replacing the control board, lift up and remove the weather stripping on the firewall (red arrow).
Figure 5

To start replacing the control board, lift up and remove the weather stripping on the firewall (red arrow). Next, use a Philips head screwdriver and remove the three screws and (yellow arrow) and remove the corner plate between the control panel housing and fender.

Unscrew the plastic retaining knob in the upper corner (red arrow).
Figure 6

Unscrew the plastic retaining knob in the upper corner (red arrow).

Using a 5mm Allen remove the single bolt in the front corner.
Figure 7

Using a 5mm Allen remove the single bolt in the front corner.

Do not lose the plastic shim that goes between the panel and housing.
Figure 8

Do not lose the plastic shim that goes between the panel and housing.

You can now lift the panel, fuses, relays and wiring harness up and out from the housing.
Figure 9

You can now lift the panel, fuses, relays and wiring harness up and out from the housing. Place a shop towel down between the panel and housing to prevent scratching the housing while you work.

Label the two incoming power lines and remove them from the panel using a 10 mm socket (yellow arrows).
Figure 10

Label the two incoming power lines and remove them from the panel using a 10 mm socket (yellow arrows).

Label and remove the relay from the top of the panel then using a small flathead screwdriver from above release the two clips (yellow arrows) on each relay and slide them out from the bottom of the panel.
Figure 11

Label and remove the relay from the top of the panel then using a small flathead screwdriver from above release the two clips (yellow arrows) on each relay and slide them out from the bottom of the panel. Make sure to label them as you remove them.

To remove all of the electrical connections you must first release the central clip that holds them to the panel.
Figure 12

To remove all of the electrical connections you must first release the central clip that holds them to the panel. At the top of the panel grab the central lock and slide it away from the panel (red arrow) and this will free up the central locks.

Now you can squeeze in the tabs on the outside (red arrow) and pull the connectors out from the panel.
Figure 13

Now you can squeeze in the tabs on the outside (red arrow) and pull the connectors out from the panel. Remember to pull them out by the connecter housings and not the wires. The connectors will only fit in the proper slots so it is pretty hard to mess this up but take pictures or label things if you have any worries. Installation is the reverse of removal.

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Page last updated: Sat 4/29/2017 03:18:08 AM