flashing shift indicator

[Scooter2525]

FWIW, the 2002-2004 Acura MDX had a notorious Transmission issue. We had an '03 and got rid of it after the second transmission started to fail. I hope the second gens will have fixed this particular issue.

[rocky]

Originally Posted by N_Jay

If it is a dealer, I would negotiate for a better price on the service
It is a $50 part, and can NOT take even an hour for a competent mechanic to replace.

Took 45 minutes to do both third and fourth gear switches

[94eg!]

So what is the consensus on the flashing shift indicator? Replace the pressure switches first? I've already done a 3x3 with Z1 about 13k miles ago (1.5yrs ago).

Stupid local dealer wants $170 for these two switches for the 04. Reno sucks.

[hp2004]

I have an '04 EX and I have the blinking "D" light too, but when I downshift to D3 that light will not blink. So....does this mean that just the forth gear pressure switch just need changing or what? Tring to save some money from buying both of the switches.

[PILOTHEAD]

After I read all the forum pages here on this subject my judgement was to first replace the 4th gear switch, see what happens, and then go back and do the 3rd if it did not stop the D from flashing. Replacing only the 4th gear switch stopped the D from flashing on our Pilot.

[hp2004]

Does anyone know the range of the switches, do they go off the mph or rpm or what? My Pilot seems to have more of an issue in the 45 to 55 mph range. So I think I'm going to switch out just the 4th gear first. Would be nict to know how these switches work.

[94eg!]

Okay here is some helpfull info for those DIY'ers out there that have experienced the flashing D light.

I found out how to pull the special Honda Transmission codes from the ECU without actually going to Honda (they don't show up on an OBD2 scanner). Take a paper clip and unbend it so you have two prongs pointing in the same direction. Now jam them into the #4 and #9 pins of your OBD2 service port like the picture below (My Pilot has the plug oriented different so pay attention).



Grab your pen & paper and sit down in the drivers seat. Now stick the key in and switch the ignition to the On position. Your D light and check engine light and VTM light will begin flashing. Pay attention to the D light for now. Record the number of long blinks followed by the short blinks for your D light. Then do the same for your Check Engine light and VTM light. In my case I had code 27 on the D light. That was 2 long blinks followed by 7 short blinks. Then I had code 70 on the check engine light. That is 7 long blinks and no short blinks.

When I go to the shop manual, Code 70 means "problem with the automatic transmission". This is a generic code and WILL show up on an OBD2 scanner as P0700 which simply tells you "go to the dealer". This only means there was A problem with the transmission. Next is where we refer to the code 27 (the real info). This won't show up on a scan tool. Code 27 means one of two things in the shop manual:

- 4th clutch fluid pressure switch (short or stuck ON)
- 4th clutch fluid pressure switch (open or stuck OFF)

Since I replaced both my pressure switches yesterday, I should be good to go now.

[PILOTHEAD]

Excellent, How did you figure this out?

I had a theory that these switchs could just be cleaned vs. replaced but never took any action on it (I just replaced with new)...with this way of yours to be able to diagnose it at zero cost...I just might try cleaning my old one and see if it would work.

So can you use this method to get all the "extended" codes that a obd2 scanner can not?

[94eg!]

Yes. But it's still not as good/specific as the Honda HDS scanner. For example, the code 27 I pulled, would be displayed on your dashboard for both an open or short condition of the 4th gear pressure switch. If you had the Honda HDS scanner, it would tell you specifically as code 27-3 for short/on or 27-4 for open/off.

The weird part is that manual reads off OBD2 style "P" codes (powertrain) for every transmission-specific code as well, but I was unable to read these with the OBD2 scan tool I borrowed from O'Reilly's. P0872 = 27-3 and P0873 = 27-4. The only one I could read with this tool was P0700 which, as I mentioned, is a generic "AT Problem" code. And I even had to put the scanner into a special "Honda" specific mode to find that one.

Here is a list of the A/T trouble codes you can get from your dashboard. This reference is from a 2004 Acura TL, so it's probably missing 4WD specific stuff. Also notice they are in an odd group order (not numerical). According to the manual the codes I've put in bold "are caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission". This means the ones not in bold are BAD NEWS!:

5 - Transmission range switch (multiple shift-position input)
6 - Transmission range switch (open)
28 - ATF temperature sensor (range/performance, short, or open)
15 - Input shaft (mainshaft) speed sensor (range/performance, intermittent failure)
9 - Output shaft (countershaft) speed sensor (range/performance, no signal input, intermittent failure)
64 - 1st, 2nd, 3rd, 4th or 5th gear incorrect ratio
40 - Torque converter clutch circuit performance or stuck off
76 - AT clutch pressure control solenoid valve stuck (ON, OFF)
70 - Shift solenoid valve A stuck (ON, OFF)
71 - Shift solenoid valve B stuck (ON, OFF)
72 - Shift solenoid valve C stuck (ON, OFF)
77 - A/T clutch pressure control solenoid valve B stuck (ON, OFF)
45 - Shift control system

24 - Transmission gear selection switch upshift or downshift switch (short or stuck ON)
26 - 3rd clutch transmission fluid pressure switch (short/ON, open/OFF)
27 - 4th clutch transmission fluid pressure switch (short/ON, open/OFF)
24 - Transmission gear selection switch (short/ON, open/OFF)
16 - A/T clutch pressure control solenoid valve A
23 - A/T clutch pressure control solenoid valve B
29 - A/T clutch pressure control solenoid valve C
7 - Shift solenoid valve A (short, open)
8 - Shift solenoid valve B (short, open)
22 - Shift solenoid valve C (short, open)
1 - Torque converter clutch solenoid valve (short, open)


BTW: I figured this out while reading and re-reading and re-reading the first couple pages of the A/T section of my 04 TL shop manual. It mentions you can get the trouble codes to display via the D light by grounding out one of the wires on your OBD-2 scanner harness. Well I knew there had to be a ground already in the plug itself, so I did a little searching. That's when I found a website that mentioned getting check engine light codes to display on your dash (that's where that picture came from). I figured it would work for the trans codes, so I tested it and it worked.

This page shows all the codes your Check Engine Light will blink out: http://www.k20tuned.com/xcart/pages.php?pageid=10

[NJGuy]

Originally Posted by PILOTHEAD

I had a theory that these switchs could just be cleaned vs. replaced but never took any action on it (I just replaced with new)...with this way of yours to be able to diagnose it at zero cost...I just might try cleaning my old one and see if it would work.

I looks more like the pressure switches typically start to fail due to wear, not due to material buildup that can be cleaned off. See the following links (they contain pretty much the same information):
Transmission failure - possible cause and fix - Page 3 - Drive Accord Honda Forums
Very interesting conversation with my transmission builder on the TL - Page 14 - AcuraZine Community

[PILOTHEAD]

Originally Posted by NJGuy

I looks more like the pressure switches typically start to fail due to wear, not due to material buildup that can be cleaned off.

Yes, now I see from the links you posted that any repair attempt would be futile, thanks for posting this, I also found the PSI cut in/out testing of old and new sensors very informative about why such noticeable differences occur in shifting after you remove and replace them.

[hp2004]

So to be sure , just switch out the switches anyway.

[94eg!]

Here is that link to the VTM codes as well. If you VTM light is blinking when you do the paperclip thing. Thanks a2mann:

http://rsgear.com/articles/2006_12.pdf