How smart is the PCM ? Can you have engine/tranny (A4) "burps" & NOT throw codes ?
Thread Starter
Registered User
Joined: Mar 2000
Posts: 835
From: HOUSTON TX USA
How smart is the PCM ? Can you have engine/tranny (A4) "burps" & NOT throw codes ?
The SS is still doing that weird hot start stumle & buck in drive which will disappear after a couple of seconds. I have never gotten a SES light when this happens.
I wrote it off to wet electronics the first time it happended, but it has gotten pretty consistent as of late.
I even took of the HPP3 this weekend - no change.
(It went right back on !!
)
Auto Zone tells me that they can't pull codes if the light isn't on - ??
I just wonder if one of the solenois internal to the tranny is spazzing & then resetting - ??
Thanks !!
Britt
------------------
'99 T/A
Best 13.071 @ 104.92
Now own '99 SS # 2073 !
12.969 @ 105.44
I wrote it off to wet electronics the first time it happended, but it has gotten pretty consistent as of late.
I even took of the HPP3 this weekend - no change.
(It went right back on !!
) Auto Zone tells me that they can't pull codes if the light isn't on - ??
I just wonder if one of the solenois internal to the tranny is spazzing & then resetting - ??
Thanks !!
Britt
------------------
'99 T/A
Best 13.071 @ 104.92
Now own '99 SS # 2073 !
12.969 @ 105.44
Registered User
Joined: Jun 2002
Posts: 78
From: Lake Worth, FL, USA
Here's a possibility -
A/T - Poor Performance/SES Lamp ON/DTC P0757 Set
File In Section: 07 - Transmission/Transaxle
Bulletin No.: 01-07-30-038
Date: December, 2001
Subject: DTC P0757 Set, SES Lamp Illuminated, Poor Performance of Transmission, Transmission Slipping
(Clean Transmission Valve Body and Case Oil Passages of Debris)
Condition: Some customers may comment on any of the following conditions:
^ The SES lamp is illuminated.
^ No 3rd and 4th gear.
^ The transmission does not shift correctly.
^ The transmission feels like it shifts to Neutral or a loss of drive occurs.
The vehicle free wheels above 48 km/h (30 mph). High RPM needed to overcome the free wheeling.
Cause: The most likely cause is chips or debris plugging the bleed orifice of the 2-3 shift valve. This will cause the transmission to stay in 2nd gear and return to 1st gear when and/or if the PCM attempts a 3-4 shift. DTC P0757 code may also be set if the 2-3 shift valve were stuck or hung-up in its bore. Inspect the 2-3 shift valve and the 2-3 shuttle valve for free movement or damage and clean the valves, the bore and the valve body passages.
Correction: The 1-2 and 2-3 shift solenoid valves (also called A and B solenoids) are identical devices that control the movement of the 1-2 and 2-3 shift valves (the 3-4 shift valve is not directly controlled by a shift solenoid).
The solenoids are normally-open (not energized electrically) exhaust valves that work in combination to shift the transmission into four different forward gears. Opening and closing the exhaust valves within the solenoids redirect the transmission fluid, hydraulically moving shift valves and the corresponding shifting of the transmission gears.
The PCM energizes (turns On) or de-energizes (turns Off) each solenoid by either grounding or removing the ground to the solenoid through a quad driver (switch) within the PCM. This allows current flow through the coil winding of the solenoid which causes movement of the internal plunger, blocking or opening an internal orifice.
------------------
'99 Z28 A4 BLACK
▪ SLP air lid, K&N filter, air box mod, Borla exhaust, HPP3, 160* stat, Magnecor 8.5 mm wires, NGK TR55 plugs
▪ Pioneer DEH-P77DH, Polk speakers
A/T - Poor Performance/SES Lamp ON/DTC P0757 Set
File In Section: 07 - Transmission/Transaxle
Bulletin No.: 01-07-30-038
Date: December, 2001
Subject: DTC P0757 Set, SES Lamp Illuminated, Poor Performance of Transmission, Transmission Slipping
(Clean Transmission Valve Body and Case Oil Passages of Debris)
Condition: Some customers may comment on any of the following conditions:
^ The SES lamp is illuminated.
^ No 3rd and 4th gear.
^ The transmission does not shift correctly.
^ The transmission feels like it shifts to Neutral or a loss of drive occurs.
The vehicle free wheels above 48 km/h (30 mph). High RPM needed to overcome the free wheeling.
Cause: The most likely cause is chips or debris plugging the bleed orifice of the 2-3 shift valve. This will cause the transmission to stay in 2nd gear and return to 1st gear when and/or if the PCM attempts a 3-4 shift. DTC P0757 code may also be set if the 2-3 shift valve were stuck or hung-up in its bore. Inspect the 2-3 shift valve and the 2-3 shuttle valve for free movement or damage and clean the valves, the bore and the valve body passages.
Correction: The 1-2 and 2-3 shift solenoid valves (also called A and B solenoids) are identical devices that control the movement of the 1-2 and 2-3 shift valves (the 3-4 shift valve is not directly controlled by a shift solenoid).
The solenoids are normally-open (not energized electrically) exhaust valves that work in combination to shift the transmission into four different forward gears. Opening and closing the exhaust valves within the solenoids redirect the transmission fluid, hydraulically moving shift valves and the corresponding shifting of the transmission gears.
The PCM energizes (turns On) or de-energizes (turns Off) each solenoid by either grounding or removing the ground to the solenoid through a quad driver (switch) within the PCM. This allows current flow through the coil winding of the solenoid which causes movement of the internal plunger, blocking or opening an internal orifice.
------------------
'99 Z28 A4 BLACK
▪ SLP air lid, K&N filter, air box mod, Borla exhaust, HPP3, 160* stat, Magnecor 8.5 mm wires, NGK TR55 plugs
▪ Pioneer DEH-P77DH, Polk speakers
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