01 prelude p0700 and p0740 check codes
06-04-2013, 05:04 PM
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01 prelude p0700 and p0740 check codes
Hello all on may 31st (last Friday) i bought my self a 2001 Honda prelude with 104000 miles on it and a auto trans. the same day that i bought the car a check engine light came on. the code that the scan showed was a p0700 and p0740 they are both trans related codes.The trans was shifting fine and car was very deliverable just would need some extra pressure some times shifting up the gears but other then that shifted fine .ive read about trying to change the trans fluid on the car and see if its dirty. im scared to do a full flush on the trans with that many miles. i wanted try a few other things before i need to drop the trans and replace the torque converter. thanks for taking the time to read this and im looking forward to any input to get my new car feeling like new
06-06-2013, 05:27 PM
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Re: 01 prelude p0700 and p0740 check codes
Replace the transmission and torque converter. You can try to do a flush (3 back to back drain-fills) but it probably wont help, P0740 is caused by a lack of pressure in the hydraulic system. P0700 is just a code telling you the trans isn't operating normally.
06-06-2013, 06:44 PM
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Re: 01 prelude p0700 and p0740 check codes
its a myth that changing that trans fluid after a lot of miles will hurt the trans. if the trans is bad than the trans is bad. changing the fluid is not going to make it worse
06-07-2013, 02:40 PM
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Re: 01 prelude p0700 and p0740 check codes
i know not to do a flush on that many miles. bu taking the pan out and letting it drain is not bad idea. i just dont want to drop the trans and do the torque converter if its just a sensor on the out side i can get to. it dose feel like a presure issue the way it shifts it hates first gear going to second. it will make lot noise trying to shift till i give it more gas or left of the gas to make it shift up.
06-07-2013, 03:33 PM
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Re: 01 prelude p0700 and p0740 check codes
I work at the dealer man, we never replace just the torque converter on any Honda in the 98-02 range, they all had terrible transmission problems. We also don't service the internals, only replace using a reman system. We may replace external sensors and solenoids but you have a internal problem with a lack of pressure, torque converter is more than likely shot and driving it like it is has probably put a good bit of wear on the clutch packs.
Also, no Honda AT has a pan, only the CVT transmissions do.
You can try to drain/fill but I doubt it'd help. Looking at service notes on that code every thing points to replacing the torque converter and AT as a pair.
There's a reason someone sold it to you, it was probably fucked up for some time.
People think it's just the Preludes that were bad but all Honda's from 98-02 had the same problems, we still replace many Odyssey, Accord and Civic transmissions to this day.
Also, no Honda AT has a pan, only the CVT transmissions do.
You can try to drain/fill but I doubt it'd help. Looking at service notes on that code every thing points to replacing the torque converter and AT as a pair.
There's a reason someone sold it to you, it was probably fucked up for some time.
People think it's just the Preludes that were bad but all Honda's from 98-02 had the same problems, we still replace many Odyssey, Accord and Civic transmissions to this day.
06-07-2013, 09:17 PM
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Re: 01 prelude p0700 and p0740 check codes
yeah most dealers prefer replacing the trans instead of trying to figure what line is clogged or going part by part from what i read. thanks mini for your reply. im going to try a few things on Monday on a lift and see if i can find a vacuum leak or a line that clogged before i go and drop the trans out and look at it from there.
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06-08-2013, 06:45 AM
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Re: 01 prelude p0700 and p0740 check codes
Just start by checking line pressure at the ports at the end of the trans, that will most likely reveal the problem. That code is usually lack of pressure caused by a bad torque converter seal.
06-11-2013, 03:19 PM
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Re: 01 prelude p0700 and p0740 check codes
i put the car onto the lift and drained the fluid out of the pan. the fluid looked red and clear just a little dirt tint and there was no signs of clutch material in the fluid. i did not get to check pressure on the lines or any thing like but i did hook it up to auto scan but that didn't give me any new info like i was hoping for in fact it only showed the p0700 and not the p0740 code. i re set the codes and so far no check engine light. I still do feel the trans working hard when im driving at 20mph and the trans is about 2k rpms. other words it shifts other gears ok just little hard shift here and there.
06-11-2013, 08:43 PM
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Re: 01 prelude p0700 and p0740 check codes
just hope its a shift solenoid
P0740 HONDA - Transmission Lock-Up Control System Fault
Possible causes
- Low transmission fluid level
- Dirty transmission fluid
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted
When is the code detected?
Diagnostic trouble code P0740 is detected when TCM detects an improper voltage drop when it tries to operate the solenoid valve.
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Transmission shift shock
- Vehicle may not shift into the highest gea
P0740 HONDA Description
The torque converter clutch solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter.
Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.
and the P1457 is not transmission related. its a evap leak
s2ki.com/stor/library/TSB/a03-001.pdf <<<<< copy and past in browser
P1457 won't make the car run bad at all. It just means the EVAP canister & the related system of hoses & valves isn't airtight like it should be.
Check this stuff in this order. As soon as you find something that doesn't behave like it should, fix or replace it. Then hope it was the only thing wrong with the system...
Some background for the electrical troubleshooting:
All the solenoid valves have constant +12v supply from the main relay. When the ECM wants to energize a valve, it closes the ground side of it's circuit. If the +12v supply is broken, then the ECM can't energize the valve. If the wire to the ECM is shorted to ground, then the valve is energized even when the ECM doesn't want it to be.
EVAP Purge Control valve - between intake manifold & valve cover.
Valve should be normally closed, so it will hold vacuum when it's not energized. Ground is supplied by pin A6 of the ECM to open the valve. So jumper pin A6 to ground, turn on the ignition, and check again - this time it should NOT hold vacuum.
EVAP 2-way valve - underneath the car roughly under the left-rear seat. It's a little can with 3 hose barbs & a solenoid valve attached to it. Leave the connection on top, disconnect both on the side, attach MityVac to lower one. Normally closed, it should hold vacuum when the solenoid is not energized. When the solenoid valve is energized, it should not hold vacuum.
************ THANKS to rjpjnk for the following clarification about this valve.
The 2 way valve is complicated. It should hold vacuum on the lower port when the solenoid is *not* energized. The solenoid when energized provides a passageway to bypass the normal path between the upper port and the lower port. That's why it is called a "bypass solenoid" btw.
The upper port of this wretched valve from pluto is actually designed to open to pass vacuum or pressure to the lower port when the vacuum or pressure exceeds a certain threshold (a kind of hysteresis effect). The slight resistance to flow is what allows a certain design pressure to remain in the fuel tank. Once this is exceeded, the excess pressure (fuel vapor) bleeds over to the canister side. At any time, the ECM can force this to happen by activating the bypass solenoid. It does exactly this during the p1456/p1457 diagnostic tests. The upper side port is always connected to the top port (the third leg of this beast) which is connected directly to the FTP (fuel tank pressure sensor). Did you know the FTP sensor is not in the fuel tank? ;-)
************
EVAP Canister Vent Shut valve - attached to the charcoal canister underneath the car.
Normaly open - when ECM closes pin A4 to ground, it should hold vacuum.
EVAP Charcoal Canister - the big can under the car, about under the left-rear seat.
Leak test: Connect all the hoses together, plug the Vent Shut valve, connect the MityVac. Pump vacuum while watching the fuel tank pressure (FTP) sensor. You can read FTP sensor voltage with a scan tool, or use a voltmeter between pins A29 & C18 at the ECM. Pump down to 1.5v & it should hold that vacuum for at least 20 seconds.
EVAP 2-way valve vacuum & pressure test.
If you get this far you'll want the manual for a good picture of how to connect the hoses. Keep pumping the vacuum pump & it should stabilize between 6 & 16 mm Hg of vacuum. Then pump pressure, it should stabilize at 8 mm Hg or more of pressure.
Then there's a test of the ORVR Vent Shut valve, which is located on top of the gas tank. You check vacuum & pressure at a couple hoses alongside the fuel filler pipe. If the valve is bad you drop the gas tank to replace it...
P0740 HONDA - Transmission Lock-Up Control System Fault
Possible causes
- Low transmission fluid level
- Dirty transmission fluid
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted
When is the code detected?
Diagnostic trouble code P0740 is detected when TCM detects an improper voltage drop when it tries to operate the solenoid valve.
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Transmission shift shock
- Vehicle may not shift into the highest gea
P0740 HONDA Description
The torque converter clutch solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter.
Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.
and the P1457 is not transmission related. its a evap leak
s2ki.com/stor/library/TSB/a03-001.pdf <<<<< copy and past in browser
P1457 won't make the car run bad at all. It just means the EVAP canister & the related system of hoses & valves isn't airtight like it should be.
Check this stuff in this order. As soon as you find something that doesn't behave like it should, fix or replace it. Then hope it was the only thing wrong with the system...
Some background for the electrical troubleshooting:
All the solenoid valves have constant +12v supply from the main relay. When the ECM wants to energize a valve, it closes the ground side of it's circuit. If the +12v supply is broken, then the ECM can't energize the valve. If the wire to the ECM is shorted to ground, then the valve is energized even when the ECM doesn't want it to be.
EVAP Purge Control valve - between intake manifold & valve cover.
Valve should be normally closed, so it will hold vacuum when it's not energized. Ground is supplied by pin A6 of the ECM to open the valve. So jumper pin A6 to ground, turn on the ignition, and check again - this time it should NOT hold vacuum.
EVAP 2-way valve - underneath the car roughly under the left-rear seat. It's a little can with 3 hose barbs & a solenoid valve attached to it. Leave the connection on top, disconnect both on the side, attach MityVac to lower one. Normally closed, it should hold vacuum when the solenoid is not energized. When the solenoid valve is energized, it should not hold vacuum.
************ THANKS to rjpjnk for the following clarification about this valve.
The 2 way valve is complicated. It should hold vacuum on the lower port when the solenoid is *not* energized. The solenoid when energized provides a passageway to bypass the normal path between the upper port and the lower port. That's why it is called a "bypass solenoid" btw.
The upper port of this wretched valve from pluto is actually designed to open to pass vacuum or pressure to the lower port when the vacuum or pressure exceeds a certain threshold (a kind of hysteresis effect). The slight resistance to flow is what allows a certain design pressure to remain in the fuel tank. Once this is exceeded, the excess pressure (fuel vapor) bleeds over to the canister side. At any time, the ECM can force this to happen by activating the bypass solenoid. It does exactly this during the p1456/p1457 diagnostic tests. The upper side port is always connected to the top port (the third leg of this beast) which is connected directly to the FTP (fuel tank pressure sensor). Did you know the FTP sensor is not in the fuel tank? ;-)
************
EVAP Canister Vent Shut valve - attached to the charcoal canister underneath the car.
Normaly open - when ECM closes pin A4 to ground, it should hold vacuum.
EVAP Charcoal Canister - the big can under the car, about under the left-rear seat.
Leak test: Connect all the hoses together, plug the Vent Shut valve, connect the MityVac. Pump vacuum while watching the fuel tank pressure (FTP) sensor. You can read FTP sensor voltage with a scan tool, or use a voltmeter between pins A29 & C18 at the ECM. Pump down to 1.5v & it should hold that vacuum for at least 20 seconds.
EVAP 2-way valve vacuum & pressure test.
If you get this far you'll want the manual for a good picture of how to connect the hoses. Keep pumping the vacuum pump & it should stabilize between 6 & 16 mm Hg of vacuum. Then pump pressure, it should stabilize at 8 mm Hg or more of pressure.
Then there's a test of the ORVR Vent Shut valve, which is located on top of the gas tank. You check vacuum & pressure at a couple hoses alongside the fuel filler pipe. If the valve is bad you drop the gas tank to replace it...
06-11-2013, 08:45 PM
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Re: 01 prelude p0700 and p0740 check codes
im going to look into a few things he said and hoping that worse comes to worse its the torque converter. if not then its a lemon : \
08-15-2014, 07:32 PM
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MM Gruppe B
08-25-2014, 09:40 AM
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Re: 01 prelude p0700 and p0740 check codes
[QUOTE=MAD_MIKE;49902212]P740 is a lockup control function issue.
But on the B7XA transmissions its usually a death note.
I wouldn't call a death note, but it can surely be rebuilt to survive another day= just did a 98 Accord w/ same code and burnt TC, had also PR valve gunked up and friction disc material from 1-2 packs that where just metal.
But on the B7XA transmissions its usually a death note.
I wouldn't call a death note, but it can surely be rebuilt to survive another day= just did a 98 Accord w/ same code and burnt TC, had also PR valve gunked up and friction disc material from 1-2 packs that where just metal.
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