01 Accord P0730 & P0780
12-03-2015, 01:46 PM
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01 Accord P0730 & P0780
Hello all I have a 2001 Accord that has about 170k miles. Over the past few years I've owned it the transmission has always shifted a little hard. The previous owner had a Honda certified dealer completely flush the transmission from the sound of what they told me. I have read that this can damage worn-in high mileage Accord transmissions.
Yesterday when shifting into d4 the transmission kicked and the d4 started blinking. The check engine also came on. I drove home in d3 with no issues.
After that the check engine is still on but the d4 no longer has functional problems. Because of this I was not able to record the blink pattern.
Today I checked with a computer and got P0730 - gear ratio incorrect and also P0780 - shift malfunction.
Is my transmission about to have a major failure or are there any steps I can take immediately to help it without some sort of rebuild? Thanks.
Yesterday when shifting into d4 the transmission kicked and the d4 started blinking. The check engine also came on. I drove home in d3 with no issues.
After that the check engine is still on but the d4 no longer has functional problems. Because of this I was not able to record the blink pattern.
Today I checked with a computer and got P0730 - gear ratio incorrect and also P0780 - shift malfunction.
Is my transmission about to have a major failure or are there any steps I can take immediately to help it without some sort of rebuild? Thanks.
12-05-2015, 06:50 PM
#2
MM Gruppe B
Re: 01 Accord P0730 & P0780
If the dealership was Honda certified they would not flush the trans but would drain/refill it.
If the transmission has always shifted hard, you may want to verify that the 2nd and 3rd gear pressure switches are not leaking. If they are it would require a greater pressure differential to activate them and a hard shift would then occur.
Removing the shift solenoids and verifying they are clean and not fouled. Same with the two shaft sensors, if they are fouled the resolution to the PCM will be less than ideal and can cause erratic/harsh shifts.
Per Honda FSM
P0730. Shift Control system *D4 does not light*
P0780. Mechanical Problem in Hydraulic System
Only way to properly diagnose these is to verify pressures of the circuits. A transmission specialist should be able to verify operating pressures.
If there are any engine codes, repair those issues first. Automatic functionality is greatly affected by the engines running condition.
If the transmission has always shifted hard, you may want to verify that the 2nd and 3rd gear pressure switches are not leaking. If they are it would require a greater pressure differential to activate them and a hard shift would then occur.
Removing the shift solenoids and verifying they are clean and not fouled. Same with the two shaft sensors, if they are fouled the resolution to the PCM will be less than ideal and can cause erratic/harsh shifts.
Per Honda FSM
P0730. Shift Control system *D4 does not light*
P0780. Mechanical Problem in Hydraulic System
Only way to properly diagnose these is to verify pressures of the circuits. A transmission specialist should be able to verify operating pressures.
If there are any engine codes, repair those issues first. Automatic functionality is greatly affected by the engines running condition.
12-06-2015, 01:18 AM
#3
Honda-Tech Member
Re: 01 Accord P0730 & P0780
These codes occur when there isn't sufficient mechanical pressure to maintain the commanded gear position. This can be caused by a handful of conditions that you should first check:
1: Proper fluid level.
2: leakage of ATF from the unit, including the pressure switches.
Since there is an incorrect gear ratio code, the transmission is slipping while it is commanding a gear shift. First, perform a stall test in the L and 2 positions to determine if the 1st or 2nd gear clutches are slipping under full load braking. In most failure cases, you will feel a violent jerk when performing this test, or excessive engine RPM above specification. This is indicative of slippage in that position, and that there is either reduced hydraulic flow to that gear's apply piston, or the clutches are completely worn out.
2nd gear is notorious for slippage, and these two positions (1st and 2nd) you can test yourself without the use of gauges to verify. 3rd and 4th will require a dynamometer (or another means of defeating traction control and shifting), and a pressure gauge set.
170k miles is a lot of miles for an original unit. Most units suffer shifting problems with "average" driving at around the 120,000 mile mark.
Your codes do not indicate an electrical fault in the solenoids themselves, but you should perform a resistance test of the solenoids to ensure the current they draw is correct. Your problem is purely mechanical: either the solenoid is shorted (less engagement power), the valve itself is stuck due to debris, or the clutch piston is over extending, and leaking fluid out of the circuit due to wear and tear.
Personally, I have had less than a handful of B7 transmissions with solenoid failures. This condition is usually caused by excessive wear on the clutches, a clogged oil filter element, a worn out transmission pump, or a leaking clutch apply piston o-ring.
It would be my best advice to you, to have the unit torn down and inspected for wear and tear, since the problem is internal in nature. A clutch pressure fault from the clutch pressure switches will not set these codes, as a DTC for the pressure fault must exist prior to these codes being set. At that point you would need to address that issue first. The clutch pressure switch failure is a nuisance failure, and generally not detrimental to the unit unless enormous amounts of fluid leak from the switches.
You also have neglected to tell us basic information. Is it a 4 cylinder, or a V6? You need to provide as much information as possible so we can point you in the right direction.
1: Proper fluid level.
2: leakage of ATF from the unit, including the pressure switches.
Since there is an incorrect gear ratio code, the transmission is slipping while it is commanding a gear shift. First, perform a stall test in the L and 2 positions to determine if the 1st or 2nd gear clutches are slipping under full load braking. In most failure cases, you will feel a violent jerk when performing this test, or excessive engine RPM above specification. This is indicative of slippage in that position, and that there is either reduced hydraulic flow to that gear's apply piston, or the clutches are completely worn out.
2nd gear is notorious for slippage, and these two positions (1st and 2nd) you can test yourself without the use of gauges to verify. 3rd and 4th will require a dynamometer (or another means of defeating traction control and shifting), and a pressure gauge set.
170k miles is a lot of miles for an original unit. Most units suffer shifting problems with "average" driving at around the 120,000 mile mark.
Your codes do not indicate an electrical fault in the solenoids themselves, but you should perform a resistance test of the solenoids to ensure the current they draw is correct. Your problem is purely mechanical: either the solenoid is shorted (less engagement power), the valve itself is stuck due to debris, or the clutch piston is over extending, and leaking fluid out of the circuit due to wear and tear.
Personally, I have had less than a handful of B7 transmissions with solenoid failures. This condition is usually caused by excessive wear on the clutches, a clogged oil filter element, a worn out transmission pump, or a leaking clutch apply piston o-ring.
It would be my best advice to you, to have the unit torn down and inspected for wear and tear, since the problem is internal in nature. A clutch pressure fault from the clutch pressure switches will not set these codes, as a DTC for the pressure fault must exist prior to these codes being set. At that point you would need to address that issue first. The clutch pressure switch failure is a nuisance failure, and generally not detrimental to the unit unless enormous amounts of fluid leak from the switches.
You also have neglected to tell us basic information. Is it a 4 cylinder, or a V6? You need to provide as much information as possible so we can point you in the right direction.
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