1540 & 1526 codes
#2
07-20-2006 | 10:55 PM
Senior Member
Joined: Jul 2005
Posts: 2,747
RE: 1540 & 1526 codes
Both codes are indicating a fault in the ABV or Air Bypass Valve system. This system controls the air charge pressure in your intake so the compressor does not over or underpressureize the intake air charge.
P1540 is just saying that there was too large of a difference between actual and target pressure.
P1525 is pointing more to the cause. It indicates that there is a problem with the electrical signal to the ABV vacuum solenoid. Faulty solenoid is the most probable cause of this code and the P1540 but would not hurt to be able to check its operation off vehicle.
This solenoid is located on the very back and upper part of the engine near the EGR valve. See diagram below might help. There are several solenoids back there so drawing below is what your target should look like. Has two vacuum lines to it and a two wire electrical connector. Wire colors are White w/ Red stripe and Black w/ Red stripe. See if you can locate that and remove from engine compartment. Carefully remove the vacuum lines as things are probably a little fragile and brittle from age and heat.
From the second diagram below you can see that battery positive and ground are being applied to the solenoid connector (note the + and - orientation on the pins of the solenoid. With battery and ground applied you should have airflow between the two vacuum ports. With no voltage applied you should have NO airflow between the two ports.
Neither of these codes should make the TCS light come on but only the check engine light.
[IMG]local://upfiles/1377/2966270DC362488699E05FC7CB4DDA65.gif[/IMG]
[IMG]local://upfiles/1377/352B9D5D299C4722B537313A9385CE61.gif[/IMG]
P1540 is just saying that there was too large of a difference between actual and target pressure.
P1525 is pointing more to the cause. It indicates that there is a problem with the electrical signal to the ABV vacuum solenoid. Faulty solenoid is the most probable cause of this code and the P1540 but would not hurt to be able to check its operation off vehicle.
This solenoid is located on the very back and upper part of the engine near the EGR valve. See diagram below might help. There are several solenoids back there so drawing below is what your target should look like. Has two vacuum lines to it and a two wire electrical connector. Wire colors are White w/ Red stripe and Black w/ Red stripe. See if you can locate that and remove from engine compartment. Carefully remove the vacuum lines as things are probably a little fragile and brittle from age and heat.
From the second diagram below you can see that battery positive and ground are being applied to the solenoid connector (note the + and - orientation on the pins of the solenoid. With battery and ground applied you should have airflow between the two vacuum ports. With no voltage applied you should have NO airflow between the two ports.
Neither of these codes should make the TCS light come on but only the check engine light.
[IMG]local://upfiles/1377/2966270DC362488699E05FC7CB4DDA65.gif[/IMG]
[IMG]local://upfiles/1377/352B9D5D299C4722B537313A9385CE61.gif[/IMG]
#3
09-25-2007 | 06:25 PM
Joined: Nov 2006
Posts: 34
RE: 1540 & 1526 codes
Thanks babyhuey
Had 1526 code thrown as well with the sluggish behavior until restart. Happened every 20-40 miles for an entire weekend. Looked on here and saw this thread. Changed all vac hoses to the vent solenoid and my 01s runs like a champ. PS: also was getting a 0421 code every 50 or so miles but so far has not tripped the 0421 cat code. Any chance these two seemingly independent problems are related or the 1526 would be causing a change in combustion to throw the cat code?
Thanks,
Anthony
Had 1526 code thrown as well with the sluggish behavior until restart. Happened every 20-40 miles for an entire weekend. Looked on here and saw this thread. Changed all vac hoses to the vent solenoid and my 01s runs like a champ. PS: also was getting a 0421 code every 50 or so miles but so far has not tripped the 0421 cat code. Any chance these two seemingly independent problems are related or the 1526 would be causing a change in combustion to throw the cat code?
Thanks,
Anthony
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