Lexus SC400 CEL

[Adam]

So I finally got to take the Lexus to the gas station (after dealing with some terrible brake issues) and on the way back to the house the car started to run like crap and the CEL came on. The engine had no power and was not running very smoothly once it came up to temperature which was a big change from how it ran cold. Fortunately, this is an OBD-I Toyota. Much like most of the OBD-1 GMs, the diagnostic trouble codes can be retrieved by jumping some pins on a diagnostic connector and watching the CEL flash.

Code 55. Knock sensor 2 circuit. The knock sensors on the 1UZ-FE are under the intake manifold. The intake manifold is two pieces with the upper plenum and the lower runners being separate parts. In addition since this is an OHC engine there is no lifter galley that needs to be covered, so under the runners there is just open space. And the starter. And the knock sensors.

When you park a car with an engine like this in your yard for a while, mice move into the area under the runners. Then they make nests. Then they chew on everything. During the timing belt job, I removed what I thought was all of the nest through the gaps between the runners, but apparently not. Using a camera scope thing that Ed borrowed from someone, I took a look further under there. Sure enough, there is still plenty of mouse nest. Taking a close look at the connector on one of the knock sensors, the insulation on the wire is clearly chewed through. Problem identified! This is apparently a common issue on the UZ family of engines, especially the trucks.

After searching some Toyota/Lexus forums, I (hopefully) identified the correct pigtail part number. A pair of those and some gaskets set me back ~$45 but the real cost is the ~6 hour install time. The knock sensors them selves are ~$100 each so I am going to do the wiring repair and test them out before buying replacements.

Stay tuned for pics!

[kevm14]

But think of all the new intake gaskets you'll have.

[Adam]

So I got new pigtails finally. Turns out you buy them in two parts, the plastic connector is one and the wire/terminal is another. Some assembly required.

The connector:

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Connector and wire section:

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Part numbers:

Code: Select all

Connector - 90980-11166
Wire - 82998-12440

They also have a wire PN that is longer (500mm) for larger repairs, PN = 82998-12590. Fun fact: the connector is used on almost every Toyota knock sensor from the 90's and 00's. Also the wire terminal is the same for almost every Toyota connector. Either part should be readily available from your local Toyota/Lexus dealer. I used Mid Atlantic Toyota in Mechanicsville, VA because they sell directly through their website http://www.midatlantictoyotaparts.com/ for less than list price with reasonable shipping charges.

Stay tuned for repair pics.