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Discussion Starter #1
Chronological list of occurrences:

First time:
Very hot day 90 plus, air conditioning on, average speed 55-65 mph. Turned off car, happened again. Slowed down to below 50 mph till I got home and it was ok.

Second time:
Two days later. Local roads average 25 mph was ok. Got on highway and within 2 miles at average speed of 55 mph it flashes again. Fairly warm day, no air conditioner. This time, I took it in to my mechanic who thought that higher speed is heating the transmission fluid and triggering a censor. He installs an external air cooled conduit to bypass the radiator just in case there's a problem there. This has worked for the past 600-700 miles until today.

Third time:
Yesterday. I was on the road all day. I drove out around 150 miles average speed 60 - 70 + mph with air conditioning without issue. On the return trip, about 100 miles in to that (250 miles driven to that point), with a load of about 200 lbs and my passenger, average speed 70 mph and air conditioner on, D light starts blinking again. I pull off the highway, turn off car, restart, turn off air conditioner, maintain 55 to 70 mph all the way home without further issue.

Today:
Nothing. Totally fine on highway but wasn't using air conditioner just in case.

My questions:
1. Was my mechanic correct about transmission fluid heating up
2. Is the air conditioner putting some kind of load on the engine resulting in the transmission to overheat
3. Is it a combination of load being carried and air conditioner
4. Is this a radiator issue
5. Possible remedies

Thanks much and sorry for the long post.
 

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If your fluid checks out,we've had a couple Transmission Sensors replaced on our 04. They weren't expensive and have been lasting well over 100,000 miles each.
 

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Discussion Starter #4
I don't remember if my mechanic checked the fluid and color. I'll ask him to take a look.

About how much were the sensors to replace?

I'll also be at a dealership on Monday to replace an airbag from a recall notice I received. I'll ask if they can scan and get the code. I just prefer not to use the dealers for maintenance and repairs.
 

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While higher temps, higher speeds, and running A/C all have the potential to raise transmission fluid temps and aggravate something that is failing in the transmission, the temps are not the cause - something is wrong, perhaps something as simple as the fluid needing topped off or changed. Or perhaps a sensor. Or perhaps the transmission is getting ready to fail catastrophically.

Check the basics (fluid level, condition/appearance/smell, when last serviced, etc.), then have the trouble codes read by the dealer. A blinking D indicates that a code is stored in the system that will point the mechanic to the problem. In areas like this, dealers are often a good first place to go as they have the proper tools to zero in on the problem.

I'd also check immediately for any signs that there is mixing of transmission fluid and coolant as cross-contamination due to a worn-out radiator is a trouble-spot on older/high-mileage Pilots.

Doesn't sound like your mechanic did even the most basic diagnostics and immediately suggested a shade-tree band-aid fix. Not good.

- Mark
 

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Discussion Starter #6
I've had the car since last November and haven't done anything with the transmission fluid. I have no idea what it should look or smell like. I'll check out some youtube videos on it. I am bringing the car in to a dealer tomorrow for an airbag replacement and will ask them to read the codes.
 

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I've had the car since last November and haven't done anything with the transmission fluid. I have no idea what it should look or smell like. I'll check out some youtube videos on it. I am bringing the car in to a dealer tomorrow for an airbag replacement and will ask them to read the codes.
On an older car, if you don't know the history of a critical fluid change like the transmission, I'd just get it changed regardless. Along with reading the trouble codes, it would be the first step to do before anything else. I don't know what the fluid change intervals are for a 2004 (the later models are governed by the MM system), but it is probably around 50K and this is a good guideline number on most cars. Honda just specifies that you do a single drain and refill which leaves about half the old fluid in the transmission, but with regular changes, this is adequate. If you want to be more thorough or suspect the fluid is very old or perhaps the wrong fluid was used, do it a two or three times with short drives between.

I would specifically avoid any "flushing" system that the dealer or a transmission shop might recommend. Just do a regular change.

- Mark
 

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Copied from an earlier post of mine - http://www.piloteers.org/forums/69-2003-2008-pilot/107938-2004-pilot-tranny-problems.html#post1114362

Your mechanic is grabbing straws until he finds the right one. I'd find somewhere that knows a bit more about diagnosing.

Your Questions:
1. Was my mechanic correct about transmission fluid heating up - very unlikely
2. Is the air conditioner putting some kind of load on the engine resulting in the transmission to overheat. - very unlikely.
3. Is it a combination of load being carried and air conditioner - unlikely
4. Is this a radiator issue - unlikely
5. Possible remedies - this is a situation where the ECU is seeing a value(s) it is not expecting, either a null (bad sensor/connection) or out of expected range (more likely) due to age/deterioration of sensor. As heat is an enemy of electrical, my swag would be a failing sensor presenting symptoms at higher end of expected temperature range, probably a 3/4 pressure switch as they are commonly the culprit.

-----------------------------

Flashing D can mean many things, there are two paths for diagnosing.

- Flashing D WITH a check engine light generally means you are in for a rebuild soon. Most of the failures that trigger a flashing D WITH a check engine light are internal.

- Flashing D WITHOUT a check engine light is *supposed* to diagnose to one of these three cheap and easily serviceable items:
1. 3rd gear pressure switch/circuit.
2. 4th gear pressure switch/circuit.
3. Trans fluid temp sensor/circuit.
Any of the above can be a fault in the switch or simply a dirty/loose connection. Flashing D WITHOUT check engine light rarely involves anything outside of the list above. If you hook up an HDS you can quickly narrow down which of the three above tripped the code and diagnose the circuit. Additionally, the 3/4 gear pressure switches are a common failure/replacement item.
 

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1. 3rd gear pressure switch/circuit.
2. 4th gear pressure switch/circuit.
3. Trans fluid temp sensor/circuit.
What are some good sources for purchasing these online?
 

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Discussion Starter #13
Thanks for all the advice. I took it in to the dealer, it was a pressure switch. $360 later... No more flashing D.
 

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Thanks for all the advice. I took it in to the dealer, it was a pressure switch. $360 later... No more flashing D.
$360 for a pressure switch?? It's a $30 part that can be installed with basic hand tools in a driveway with only one tire removed in about 20 minutes. I did both, 3rd and 4th gear switches, in under an hour.
 

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Discussion Starter #15
$360 for a pressure switch?? It's a $30 part that can be installed with basic hand tools in a driveway with only one tire removed in about 20 minutes. I did both, 3rd and 4th gear switches, in under an hour.
Honda charged $120 for the part, $99 for the diagnostic, rest was labor for the part being put in. Took about an hour.
 

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Honda charged $120 for the part, $99 for the diagnostic, rest was labor for the part being put in. Took about an hour.
This is why I decided to do some of this stuff myself. What I found is that the hardest part was having the guts to try. Obviously, I'm not tearing into my engine or anything like that!!
 

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Wow, I had no idea a Honda dealer would charge that much to change a pressure switch. :eek:

I also proactively replaced my 3rd & 4th gear switches a couple of years ago after reading about it here. It cost me about $75 in parts and less than an hour of my time.
 

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I replaced both my 3rd and 4th pressure switch with parts from Amazon for $54. It is an easy job. Here is a youtube video howto for the Accord, the Pilot is the same.


I think what Gideon paid the Honda dealership is about right for dealership prices. You have a choice DIY or pay the prices.
 

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Copied from an earlier post of mine - http://www.piloteers.org/forums/69-2003-2008-pilot/107938-2004-pilot-tranny-problems.html#post1114362

Your mechanic is grabbing straws until he finds the right one. I'd find somewhere that knows a bit more about diagnosing.

Your Questions:
1. Was my mechanic correct about transmission fluid heating up - very unlikely
2. Is the air conditioner putting some kind of load on the engine resulting in the transmission to overheat. - very unlikely.
3. Is it a combination of load being carried and air conditioner - unlikely
4. Is this a radiator issue - unlikely
5. Possible remedies - this is a situation where the ECU is seeing a value(s) it is not expecting, either a null (bad sensor/connection) or out of expected range (more likely) due to age/deterioration of sensor. As heat is an enemy of electrical, my swag would be a failing sensor presenting symptoms at higher end of expected temperature range, probably a 3/4 pressure switch as they are commonly the culprit.

-----------------------------

Flashing D can mean many things, there are two paths for diagnosing.

- Flashing D WITH a check engine light generally means you are in for a rebuild soon. Most of the failures that trigger a flashing D WITH a check engine light are internal.

- Flashing D WITHOUT a check engine light is *supposed* to diagnose to one of these three cheap and easily serviceable items:
1. 3rd gear pressure switch/circuit.
2. 4th gear pressure switch/circuit.
3. Trans fluid temp sensor/circuit.
Any of the above can be a fault in the switch or simply a dirty/loose connection. Flashing D WITHOUT check engine light rarely involves anything outside of the list above. If you hook up an HDS you can quickly narrow down which of the three above tripped the code and diagnose the circuit. Additionally, the 3/4 gear pressure switches are a common failure/replacement item.

I'm relieved to find this post. I was just now on my way home from work and noticed the flashing D. There were no other malfunction indicator lights on, just the flashing D. I pulled over as soon as possible and turned off the engine. While I was seeing the flashing D, I did not notice that the tranny seemed to be behaving any differently than normal. I was on a backroad that I normally do not take and it has some steep inclines. When I shut off the engine I checked the fluid and everything seemed to check out ok. I started the engine back up with no flashing D. I drove it home and everything seemed normal. I had the tranny fluid changed at the dealership about 4K miles ago. I am the second owner and have all maintenance records since the pilot was new and know that it has had regular tranny maintenance. Due to things I read about issues with "flushing" a high mileage tranny, I had them do a drain and fill. I have 188K miles on my pilot.

Based on what I have described can I assume it might be one of the 3 items quoted above? I'm really hoping I'm not looking at a catastrophic tranny problem here! Any help or advise is greatly appreciated!
 

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I took pilot into the independent shop I use. The diagnostic code is PO848 3rd gear pressure switch failure. The light is currently off. If it flashes, it goes off when I turn off and restart and stays off for a week or so before it starts flashing. My question is, since it's going to be 2-3 days before I can get into the shop to have the switch replaced, am I risking doing damage to the tranny if I keep driving it? I don't have a spare car so really need the pilot to get around but certainly don't want to risk doing something that requires replacing the tranny. Appreciate any advice!
 
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