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Hi all... I had code P1738 pulled --2nd clutch pressure switch issue. Local mechanic referred me to a transmission shop. I asked if I simply needed the switch replacement or was there something more going on. I haven't noticed any issues while driving, no fluid problems, etc. The mechainic thought that the pressure switch was just a symptom of a larger issue and that a new or rebuild was in my future. What has been your experience? 2001 Ex with 145K miles. Original transmission as far as I can tell.

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I would be checking the switch and its circuit first before I splurged on another transmission.
 

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I would be checking the switch and its circuit first before I splurged on another transmission.
+1....

Rebuilt is in the 3k neighborhood, switch is $50... you could do the flush and fill, put in a new switch and see if it works. If it doesn't you probably will be able to use the new switch for the rebuilt :DD
 

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Don't listen to the tranny shop. Replace the switch. If you have not done so already install a Magnefine Inline Tranny Filter. Some may disagree, but I would also change out your current ATF and switch it over to a high quality synthetic ATF...I am having great success with the Amsoil ATF.

Same thing happened to me and a local tranny shop and the Honda dealer both couldn't wait for a tranny install job.
 

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I had my transmission (1999) rebuilt just few months ago (about 5K). The shifts from 1 to 2 were getting progressively worse; sort of like hanging and then banging. I hooked up the scanner. There were no codes. I decided to reset the ECM. After reset, the shift quality improved. But when I put the scanner again, there was P1738 DTC present. Even after resetting it few times, it comes back immediately. How in the world resetting the ECM started giving me DTC which was not there before :-( It is definitely not a coincidence that it started doing it after the reset. Interestingly, this stored code has not yet turned on MIL or TCS or flashing D4. I believe on rebuild, they use the same solenoid and pressure switches, so taking it back to the transmission shop is probably not worth it. Besides this rebuilt was done by a shop in VA because the transmission blew up after the guy in MA had rebuilt it and warrantied it. Technically, it is still under the original 3yr/36K mile warranty but I don't think pressure switches are any way.

Obviously, I will have my regular mechanic replace the switch, assuming it is outside of the transmission and easy enough to get to once the van is on the lift.

Any advise??

Thanks,
- Vikas
 

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I found out that 2nd gear pressure switch and 3rd gear pressure switch take the same part on 1999-2001 model. It is "28600-P7Z-003 Oil Pressure Switch".

Interestingly, on my van at 90K the 3rd gear pressure switch was replaced but I had the CEL on because I also had P0420 code along with P1739. Looking at the paperwork, the dealer charged me 1.5 hours for that 5 minute job. I was dumb then (and still am :) He of course charged me over the retail for the part too. It was over $200 for 3rd gear switch replacement.

I found ebay source for that switch. He claims new, OEM but I am not sure if it comes in retail packaging or not. His price is lot cheaper than local or even internet.

I just went through reading all about replacing the pressure switches here and on Acurazine. It looks like the worn out switches cause majority of the initial problem with the Honda transmission. Theory is that they lead to slippage, which leads to clutch burning, which leads to blockage in tiny passages, leading to high temperature, eventually clogging and blowing up the transmission. I think the theory does make sense and I have seen actual pressure tests done on new vs old sensor.

Both the switches are easily seen from the top and access should be easy once the lower rubber shield is removed once on the lift.

One thing which bothers me is that most of references to switch replacement has been for Acura and Pilot models, NOT on Odyssey. I recall Odypro (?) who replaced the switches and got another 9K miles before he had to do rebuild but I don't recall anybody else doing this.

- Vikas
 

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I had my mechanic put those switches in. I was wrong about the 2nd gear switch. What I thought was the 2nd gear switch was actually one of the solenoid. The actual 2nd gear switch is at an impossible place. I am amazed how my guy was able to not only replace the switch but also fix the disconnected wire from the connector. The disconnected wire explained the OBD code. I was not even able to see the 2nd gear switch but he managed to do replacement all by feel alone. Initially he thought he would have to start taking apart the throttle intake tube and bunch of other stuff but he managed to this without removing anything. He is great. The 3rd gear switch was piece of cake. Since it had about 70K miles on it, we replaced it as a maintenance item.

It fixed the OBD code and also seems to have fixed the bad 1-2 shift but I need to put more miles on it before knowing it for sure.

I felt guilty when he only charged me for half an hour ($33.50) labor to change those two switches. I need to give him a nice Christmas present.

I was hosed on washers for those switches. I had to buy them from my local dealer and they charged me $10 for two aluminum 10mm washers :-( I called couple of dealers and they all had the same price. But I saved on the switches by getting them off ebay; so $55 for switches, $10 for washers, $33.50 for labor. I managed to get them replaced for under $100. A dealer would have charged three to four hundred for the same repair.

From what I have learned from Acura website, these switches are major contributor to the eventual failure of the transmission. The explanation made sense to me.

- Vikas
 

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It is buried under the big black air flow duct tube going to the throttle body. As I said in my previous reply, I was not even able to see it. Buy a new one on ebay and then look for the old one on the transmission. Other option is to take off the air cleaner box and that tube. I *think* one should be able to see it then. Do you have the associated code P1738? If that code comes back immediately on start up, then most likely the connector (or the wire from the connector) have came off.

- Vikas
 

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Hi sontakke,

No I don't have any code. Should I change the 2nd gear switch without any code?
I have changed the Solenoid Assy Shift Part # 28200-P0Z-003 and SOLENOID ASSY LINEAR part # 28250-P6H-024 and pressure drain & fill fluid.
on my 1999 Ody, it has still littel jerk from 1 to 2 up shift, but it improve the 2 to 3 and 3 to 4 up and down shifts.

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Remember, with that code, you will NOT have the check engine light. You need to have the scanner hooked up even though the CEL is off if you want to know if you have that code or not. There are two pressure switches, for 2nd and 3rd gear and they slowly wear out. If they are still original, replace them as maintenance to prolong the life of the transmission. I think you should at least replace the 2nd gear to try to see if the jerk from 1 to 2 goes away.

- Vikas
 

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Hi Sontakke,

I have scnned from Honda I got some error about EGR not for A/T or any other belong to solenoid

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Excessive flare on 1-2 upshift

Hi Sontakke,

I have scnned from Honda I got some error about EGR not for A/T or any other belong to solenoid

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Hi 786,
I think I am seeing similar symptoms (will verify in the next few days): I still have some flares especially when engine is cold after recently replacing ATF, adding magnefine filter, and replacing the following 4 solenoids (and corresponding strainers, O-rings, and gasket): 28200-P0Z-003 SOLENOID ASSY., SHIFT; 28400-P6H-013 SOLENOID ASSY. (A) (KEIHIN); 28500-P6H-013 SOLENOID ASSY. (B) (KEIHIN); 28250-P6H-024 SOLENOID ASSY., LINEAR

I will pay attention in the next few days to see if
1. flare happens when engine is warmed up
2. flare happens on 2-3 upshift or 3-2 downshift
3. flare happens on 2-1 downshift
4. there are any codes (though there is no Engine Check light)

BTW, the EGR code is probably an entirely different thing - the EGR port being blocked. I had that too - cleaned the EGR port and then it was fine.

Like New Dad New Van says, I am guessing I may have to replace the 2nd Clutch pressure switch.
 

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It fixed the OBD code and also seems to have fixed the bad 1-2 shift but I need to put more miles on it before knowing it for sure.
So after replacing the 2nd and 3rd Clutch Pressure Switches and about a month of driving, has the shifting (especially the 1 to 2 gear shift) improved?
 

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Yes, indeed. Knock on the wood, but it has not shifted funny after the replacement. So if that is the only code, then replacing the switch would be the correct solution. For the people who also have P0740, I am not sure if they will be able to get rid of the bad shifting though.

- Vikas
 

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That is promising news then.

Yes, the P0740 and the P0730 codes are the codes you DO NOT want to get.
 

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Hi 786,
I think I am seeing similar symptoms (will verify in the next few days): I still have some flares especially when engine is cold after recently replacing ATF, adding magnefine filter, and replacing the following 4 solenoids (and corresponding strainers, O-rings, and gasket): 28200-P0Z-003 SOLENOID ASSY., SHIFT; 28400-P6H-013 SOLENOID ASSY. (A) (KEIHIN); 28500-P6H-013 SOLENOID ASSY. (B) (KEIHIN); 28250-P6H-024 SOLENOID ASSY., LINEAR

I will pay attention in the next few days to see if
1. flare happens when engine is warmed up
2. flare happens on 2-3 upshift or 3-2 downshift
3. flare happens on 2-1 downshift
4. there are any codes (though there is no Engine Check light)

BTW, the EGR code is probably an entirely different thing - the EGR port being blocked. I had that too - cleaned the EGR port and then it was fine.

Like New Dad New Van says, I am guessing I may have to replace the 2nd Clutch pressure switch.
1. Flares when engine is warmed up
2. Flare happens on 1-2 upshift
3. Flare happens on 2-3 upshift
4. No engine code

I sent the old oil (which was in there for about 30k miles) to Blackstone Labs for analysis. It came back with high levels of abrasive contaminants. They report the levels observed in my van versus the universal averages they see in all cars. Aluminum (116 in my car vs 30 as universal average), iron (449 vs 64), and silicon (77 vs 11).

I have a sinking feeling that solenoid replacement has not made a difference. And that the tranny is wearing out. Any suggestions on extending its life? The only thing I can think of doing is to replace ATF fluid 2 more times to replace as much of the old oil as possible.
 

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