Editing Z31/TCU php (section)

=== Pro Tip: Finding the Timer Control Unit (TCU) ===

The Factory Service Manual (FSM) makes it sound simple:

* Remove R.H. dash side cover and remove blower motor.
* Remove time control unit with harness connected.

Sounds easy, right? But if you can't spot the TCU after these steps, you’re not alone! Here’s how you actually get it out:

* Remove the glove box.
* Remove the lower passenger trim panel.
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Disconnect the wiring harness on the right side (the one with the 4 large plugs in it). Unscrew it from the firewall.

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You can now see the bottom corner of the TCU (just barely) if you lift up the rubber pad:

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Here comes the fun part. You have to remove the ENTIRE fan assembly to get to the TCU. This means not only removing the motor, but EVERYTHING above it. There are two screws holding it on attached to the firewall (where the passenger’s feet would be) and a third above the glove box. (Below: bad photo, but you’ll see the screw looking straight up from where the glove box was.)

* Disconnect any electrical connector that gets in the way. You may also want to disconnect the vacuum line (for auto AC).
* Lift up on the blower unit and push back about 1/2". This unhooks it from the top.
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Wiggle and curse it down until your passenger floorboard looks like this. You don't have to completely remove it from the car, but get it low enough to get to the TCU.

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NOW, you can get to the TCU to remove it. There is only one screw holding it on, and the wiring harness.

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Now that it’s out, curse the engineers a bit. Here is a picture of the TCU:

* Put in your new (or old) one and reverse the steps. Might want to check and make sure the replacement works first. And, pro tip: disconnect the Autometer gauges or radio you hooked up that caused it to blow in the first place, or you’ll be doing this again!