Originally Posted by OhRDX

I've had to mess with all these switches.

I believe this one is on the front of the trans wich is facing the front of the vehicle. Take the under tray off, drivers side, should be a few inches up facing the back of the bumper. Pretty easy to get to. Switches are about $25 from company I can't remember name of but can be found many places online.

Mine had a broken wire, check that first.

Originally Posted by FreshMeat

I think I found it in the manual. Looks very straight forward.

Originally Posted by dcmodels

Replace the transmission pressure switches as preventative maintenance. When they begin to fail, they do not always simply fail and report an DTC error. They are an electro-mechanical switch, that wears, becomes weak, and falls out-of-specification. That causes excessive wear on the clutches, because the switches affect the shifting process of the transmission.

There are three types of pressure switch failure:
Ø FAILED OPEN: electrical failure reports a DTC

Ø FAILED CLOSED: electrical failure reports a DTC

Ø FALLS OUT OF SPECIFIED-PRESSURE OPERATIONAL RANGE: mechanical wear causes the switch to function improperly, no DTC reported, extra or excessive wear occurs on the transmission clutches

WHY REPLACE THESE SWITCHES:
Obviously if a DTC is reported, replacing the failed switch is required, in order to correct/ remove the DTC. The same trans pressure switch design has been used in all Honda/ Acura automatic transmissions since about the year 2000. The part numbers differ, depending upon the model vehicle, but when you look at the operational specs, there is little or no difference between the different switches. Also note that the same part number *is* used for several years and models of both Honda and Acura vehicles.

Each pressure switch contains both an electrical part, and a mechanical part. Electrical parts tend to fail *hard*, that is, they either work, or they don’t. Mechanical parts just wear, and no longer function at the original optimal specification, but they still *work*.

When a transmission pressure switch falls out of the specified-pressure operational range, it no longer shifts the transmission between gears as its supposed to do. That causes unnecessary wear on the transmission gear clutches. The only *solution* is to change the switch before trans clutch damage occurs.

Since every Honda trans since (about) 2000 uses these same design pressure switchs, it does not matter which vehicle model uses which transmission. There are dozens of threads, on many different Honda and Acura forums, discussing the replacement of trans pressure switches, either as PM (preventative maintenance) or to *fix* some real or perceived shift problem.

I changed my own 2009 RDX switches at around 52K miles, and 5+ years. Whether or not you change the switches in your own transmission, and at what mileage, must be your decision. You can read the LINKS below, and the secondary links, to help you make that decision.

LINKS FOR MORE INFORMATION:
LINK: failed ’08 RDX 3rd gear pressure switch at 70K miles

AcuraZine Community> AcuraZine RDX Community> First Generation RDX (2007-2012)
3rd Gear Pressure Switch

https://acurazine.com/forums/first-g.../#post15191863

LINK: reported RDX bad trans 3rd pressure switch at 81K miles, post #94 and #95 and #96

AcuraZine Community> AcuraZine RDX Community> First Generation RDX (2007-2012)> Problems & Fixes
A/c not working

https://acurazine.com/forums/problem.../#post15171138

LINK: how to replace TL transmission pressure switches, with pictures, post #7

AcuraZine Community> AcuraZine TL Community> Fourth Generation TL (2009-2014)> Problems & Fixes
5AT Transmission Oil Pressure Switches

https://acurazine.com/forums/problem...itches-913431/

LINK: graph of failing pressure switch, and specified operational pressure, pictures, post #574 and #599 has a link to a discussion of why a failing switch causes transmission wear. The pictures of the switches will help you *find* the switches on your own vehicle transmission, i.e., it helps if you know what you are looking for.

AcuraZine Community> AcuraZine TL Community> Third Generation TL (2004-2008)
A-110: DIY Guide to replacing 3rd & 4th gear pressure switch for 3G TL (2004-2006)

https://acurazine.com/forums/third-g...729149/page15/

WHERE ARE THE SWITCHES LOCATED?
The easiest switch to replace is the 3rd gear switch. Try that one first, to decide if you want to do the other two, which are more difficult.

The switches are screwed into the outer case of the transmission. Depending upon the year and model of vehicle, the switches can be replaced with some effort. Unclip the electrical connector, unscrew the switch, similar to removing a large bolt, and replace with a new switch, using a new aluminum crush washer.

The problem is simply accessing the required external area of the transmission case. That requires removal of either a few parts, or many parts, which obstruct direct access to the transmission case.

Each location of each switch depends upon the year, model, and configuration of the exact transmission in your own vehicle. So you need to obtain (from a dealer or online) a graphic diagram of your own transmission, and the exact switch part numbers, for your own vehicle.

But, in general, the three switches on a Gen-1 RDX are located:
Ø Lower front driver-side of the case, near the transmission serial number, which is riveted to the case.
Ø Top middle of the case
Ø Rear passenger-corner top-side of the case

Please note that the specific descriptions below, are for my own 2009 RDX. Again, you must confirm location and switch part numbers for your own specific vehicle. The link above for the TL 5AT switches, shows pictures that are very similar to the 5AT RDX transmission in my own 2009 RDX – close enough.

4TH GEAR SWITCH:
Located on the top center of the transmission case. Remove the engine air cleaner intake box, and it is located directly under. If a short handle ratchet wrench is used to remove and install the new switch, it is not necessary to remove the battery and cover. But if a torque wrench or longer handle wrench is used, there will not be sufficient space to swing the handle, without removing the battery.

A 12-point deep 22mm socket, that has been shortened by about 3/4 inch in length, is required.

If a torque wrench is not used, then lube the new aluminum sealing washer with ATF. Then tighten the new switch by turning it about 1/8 turn or 45 degrees after its finger-tight, possibly less. A 60 degree turn is one *flat* of the switch, from one flat to the next flat in the same position, where the socket fits on the switch. Try to estimate the 1/8 turn and imagine it in your mind, before beginning.

Remember, the threaded end of the switch is only 10mm, and is hollow. You do not want to either crack the switch, or strip the aluminum threads in the trans case. But you don’t want the switch to leak ATF. It’s a delicate balance.

3RD GEAR SWITCH:
Located on the driver side lower front of the transmission case. Remove the front splash shield. Remove the driver side inner wheel well cover, which will also require removal of the wheel splash guard (if equipped). To assist removal of these parts, lift the front of the RDX, and support with jack stands. Turn the wheels fully to the left. That will allow access to all attachment bolts and clips.

The switch can then be removed using a socket and an extension straight through the wheel well. A torque wrench is easily used. Note the amount of rotation of the wrench handle, when tightening the switch, from finger tight to the proper torque. You can then use that same amount of rotation, when tightening the other two switches, so that a torque wrench is not required.

For the 2009 RDX the required pressure switch torque is 14 ft-lbs. I lubed the switch sealing washer with ATF, and used a torque of 130 in-lbs (10.8 ft-lbs). The decrease in torque, was because the washer was lubed, not dry.

2ND GEAR SWITCH:
I HAVE NOT YET REPLACED THIS SWITCH. When I do manage to do so, I will post further information on my success. If anyone else does so in the meantime, I would certainly be interested in how you did it.

Located on the passenger side rear-corner of the top of the transmission case. To access, remove the battery. Remove the air filter intake box. Remove the Air pipe bypass outlet, and the Pump assembly purge jet (bolted to the side of the air intake pipe into the turbo).

Also, a few clamps and hoses will need to be loosened and moved to one side. Try not to disconnect hoses unless necessary – just unbolt the supports/ clamps and move aside if possible. There are enough parts that you may also wish to take a picture before starting, as it can be difficult to remember how to put everything back the way it was.

Use a SK 22mm stubby 12-point combi-wrench, length about 7 inches. I could not find this wrench locally, so used a longer wrench, and cut the open-end off with an air-wrench/ cutting wheel.

--eof