Thursday, March 15, 2012

Acura TL code P0700, code P0847

2004 Acura TL Base 3.2L, V6, MFI, SOHC, Eng Desg J32A3

Problem: Automatic transmission malfunction code P0700 is set. The D light will flash. 3rd clutch transmission fluid pressure switch code P0847 is set. Freeze frame data showed all three shift solenoids were off (4th gear) when the code set. The transmission shifts fine.

Tests: 
1. Backprobe and check the voltage for the 3rd clutch transmission fluid pressure switch on the Blue/White wire, at the 3rd clutch transmission fluid pressure switch, or on the Blue/White wire at terminal C5 at the PCM. The PCM sends out a 5.0 volt reference to the 3rd clutch transmission fluid pressure switch and the 3rd clutch transmission fluid pressure switch closes to ground (near 0 volts on the Blue/White wire) when there is 3rd clutch pressure. There should be 3rd clutch pressure when the transmission is in 3rd gear. There should be approximately 5.0 volts on the Blue/White wire when there is no 3rd clutch pressure - not in 3rd gear.

2. Backprobe and check the voltage for the 4th clutch transmission fluid pressure switch on the Blue/Yellow wire at the 4th clutch transmission fluid pressure switch or on the Blue/Yellow wire at terminal C13 at the PCM to see how it responds since the code set with the transmission in 4th gear. The PCM sends out a 5.0 volt reference to the 4th clutch transmission fluid pressure switch and the 4th clutch transmission fluid pressure switch closes to ground (near 0 volts on the Blue/Yellow wire) when there is 4th clutch pressure. There should be 4th clutch pressure when the transmission is in 4th gear. There should be approximately 5.0 volts on the Blue/Yellow wire when there is no 4th clutch pressure - not in 4th gear.

Potential Causes:  3rd Clutch Transmission Fluid Pressure Switch
Automatic Transmission

Confirmed Fix: Replaced 3rd Clutch Transmission Fluid Pressure Switch: Replaced both the 3rd clutch transmission fluid pressure switch and the 4th clutch transmission fluid pressure switch. The dealer had several in stock.
Replaced 4th Clutch Transmission Fluid Pressure Switch

Tech Tips: Trouble code P0700 in the Powertrain Control Module (PCM) just indicates there is a malfunction in the transmission. Need to check transmission codes to determine what the transmission malfunction is. Since freeze frame data showed all three shift solenoids were off (4th gear) when the code set, maybe the 3rd clutch transmission fluid pressure switch was still ON in 4th gear. Since the transmission shifts fine, it is more likely a defective 3rd clutch transmission fluid pressure switch.

Wednesday, March 14, 2012

Ford F-150 The Malfunction Indicator Light (MIL) is illuminated and the Powertrain Control Module

VEHICLE: 2009 Ford F-150 XLT 4.6L, V8, MFI, SOHC, VIN 8, Eng Version Triton

MILEAGE: 18,963

Problem: The Malfunction Indicator Light (MIL) is illuminated and the Powertrain Control Module (PCM) set Keep Alive Memory (KAM) codes P0171 and P0174.

The scan tool is showing one Long Term Fuel Trim (LFT) value at (+)6% and the other at (+)129%.

Tests: 1.
The LFT value that is displayed at 129% is an illogical reading. Fuel trim is a closed loop adjustment to the air fuel ratio sensor input readings. These values go positive, in the case of a lean running condition, or negative, in the case of a rich running condition. The value itself is a percentage of adjustment one direction or the other away from the base calculation of fuel injector pulse width. The base calculation is made based on the input values of the open loop sensors such as engine RPM, Mass Air Flow (MAF) sensor input, Intake Air Temperature (IAT) sensor and Cylinder Head Temperature (CHT) sensor. The LFT maximum movement from 0% is 25% positive or negative, and the SFT maximum from 0% is 33%, positive or negative, on most scan tool displays.

2. For the PCM to set codes P0171 and/or P0174, the fuel trim (SFT or LFT) needs to reach its maximum positive limit. Any double digit value of SFT or LFT can be considered excessive correction for a lean running condition.

3. When both banks are showing lean operation at idle speed but the values decrease to single digit readings in an off-of-idle running condition, the suggestive cause is a vacuum leak concern.

4. If the fuel trim values are seen to be high in off-of-idle conditions, it would suggest a MAF sensor input or fuel delivery issue.

Check fuel pressure. This vehicle has a mechanical returnless fuel system. Fuel pressure should indicate a constant reading of 50-70 PSI.

5. If the MAF sensor input is suspect for cause, inspect the MAF sensing wire for contamination and clean it using a MAF sensor safe cleaning agent. Do not blow dry the sensing element or wipe it with a cloth or cotton swab. Touching the sending element could cause it damage. Inspect the air filter element and air cleaner assembly for a potential airflow diversion which could cause a sensing issue for the MAF and address as needed.

6. If the MAF sensing element is cleaned or the MAF is replaced, clear the PCM's adaptive memory and recheck the SFT and LFT readings on the scan tool during closed loop operation to determine if there is still indication of lean running.

Potential Causes: Vacuum Leak

Air Induction Leak

Mass Air Flow (MAF) Sensor

Fuel Pump

Fuel Filter

Confirmed Fix: Replaced Mass Air Flow (MAF) Sensor

Mercedes benz Fill Transmission fluid

VEHICLE: 2009 Mercedes-Benz C300 4Matic Sport 3.0L, V6, MFI, DOHC, Eng Desg 272.948

MILEAGE: 80,000

Problem How is transmission fluid filled after service? There is no fill tube.

Tests: 1.
Identify the transmission type. If the transmission has a fluid fill tube without a dipstick, the transmission is a 5-speed 722.6. If the transmission has no tube, it is a 7-speed 722.9.

2.
With a 722.9 transmission, it is required to fill the transmission by using the drain in the pan. When the transmission pan is removed and filter replaced, start by adding 4 1/2 quarts and start the engine.

3.
Use a factory type scan tool to read transmission temperature. When at 40 deg. C and not more than 45 deg. C, fill fluid into the drain hole. Remove the tool and watch for the amount of fluid that drains out. With no fluid or a small amount draining back out, the fluid is not full enough. With large amounts of fluid draining out, wait until the stream is reduced to the size of a pencil.

Potential Causes: Information Only

Confirmed Fix: Performed Automatic Transmission Service: 5.5 liters

Tech Tips: Special tools are required to fill the transmission. Always use factory fluid. Always replace the transmission pan bolts and follow the torque procedures or they will break.

How to fill mercedes benz transmission fluid

Honda Accord will not start

VEHICLE: 
2002 Honda Accord EX 3.0L, V6, MFI, SOHC, Eng Desg J30A1

MILEAGE
135,583

Problem
Intermittent no start. When the engine does not start, there is spark but no fuel pressure.

Tests, diagnostics 
1. Locate the Programmable Fuel Injection (PGM-FI) main relay, under the driver's side of the dash, by the brake pedal. The Black/Yellow (BLK/YEL) wire powers the fuel pump.

2. When the key is turned on, the Engine Control Module (ECM) will ground the Green/Yellow (GRN/YEL) wire for 2 seconds so the fuel pump will operate.

3. If there is no or low voltage on the BLK/YEL wire, then verify that the Red/White (RED/WHT) wire has good battery voltage. If the circuits are OK, then the common failure is the PGM-FI main relay.


Potential Causes:

PGM-FI Main Relay

Ignition Switch

Confirmed Fix:

Replaced Programmed Fuel Injection (PGM-FI) Main Relay

So there is a conformed fix on a honda accord no start