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Small but mighty

The Honda pressure switch has a lot of say in what goes on in today's transmissions.
Wednesday, May 29, 2013 - 13:56
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The Honda pressure switch has a lot of say in what goes on in today's transmissions.

Color is Important
You will find quite an assortment of different colored connectors and part numbers available for these switches. Other than that, they essentially look the same and can be easily mixed up (see Figure 5). The different colored connectors are there for identification. They identify an internal mechanical difference between each type of pressure switch. Each of the different color coded pressure switches are designed to close and open at different pressures. This is done via a small internal metallic dome that is designed to move at a specific pressure.

FIgure 4

We can’t say this enough, timing is everything. That little metallic dome inside is a moving part. It can wear out and cause the pressure parameters to change inside the switch. In turn, the computer will start telling the transmission to shift at the wrong time and you will start to feel those drivability symptoms we talked about earlier. We have also seen the dome get stuck due to fatigue or debris. It is important to take note that the computer will not always give you a pressure switch code when the switch has gone out of its pressure parameters because the switch is still functioning. It will usually give you a code if the switch is stuck.

Vehicle wiring and connection problems can also cause big issues with these pressure switches. We brought a 2000 Accord V6 into our shop with a flare on the 1-2 shift. The 2nd clutch pressure switch connector looked OK. But upon taking a closer look, we noticed that the connector clip was not fully seated. We gave it an extra push until the clip seated, and went out on a test drive. Problem solved.

Figure 5

Excessive resistance in the connection was caused by the clip not being fully seated. This is actually a highly common occurrence out in the field after a fresh install job. We have fixed many of these issues on our tech calls just by asking the mechanic to unplug the connector and plug it back in. We also have seen other wiring issues such as pinched wires, inferior butt connections and the spade connector not properly seated in the connector housing. Paying attention to these important details can save you an unnecessary R&R job and get your customer in and out of your shop as quickly as possible.

The pressure switch might not always be your problem, but it is important to not overlook it in your diagnostic procedures. You may find out that you had to do a lot less work than you thought. 

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