o2 sensor problem code 135
Thread Starter
|
New User
Joined: Sep 2003
Posts: 4
Likes: 0
o2 sensor problem code 135
I have a 2000 ford ranger with 4 cylinder engine. I am getting a code of P135. I have checked the heat in the front sensor it reads 4 ohms. I got a schematic and checked voltages at the PCM. I found that the ground at pin 95 is delayed about a minute before making ground. I am using a volt meter on pin 95 and am reading 12 volts until the ground makes. I can read pin 93 with the volt meter and the ground makes as soon as I start the engine. If you can help me with this problem I would appreciate it.
Thank You
Jim
Thank You
Jim
Moderator
Joined: Jan 2001
Posts: 56,997
Likes: 2,743
From: Virginia
My book doesn't go that late, and I can't look up the code. Plus I don't have any schematics that late either. But what I can warn you about, is a "ground" on a pin is usually a sign that the circuit is active.
Most of the computer circuits on vehicles work in reverse of what you normally think. They usually send 5 or 12 volts out to the sensor, or motor/coil/heating element all the time, as soon as the truck is started. But none of this stuff has a complete circuit back to the negative of the battery. Instead, the negative goes to the computer pin, and the computer "grounds" the wire inside with the electronics. So when you read 12 volts on a pin, that means the heater element has 12 volts on both of it's terminals, so there is 0 volts across it. The negative going to the computer pin floats up to 12 volts. When the pin at the computer goes negative, that means the computer is turning the element on, having 0 volts on one side, and 12 volts on the other(the constant feed 12 volts).
Most of the computer circuits on vehicles work in reverse of what you normally think. They usually send 5 or 12 volts out to the sensor, or motor/coil/heating element all the time, as soon as the truck is started. But none of this stuff has a complete circuit back to the negative of the battery. Instead, the negative goes to the computer pin, and the computer "grounds" the wire inside with the electronics. So when you read 12 volts on a pin, that means the heater element has 12 volts on both of it's terminals, so there is 0 volts across it. The negative going to the computer pin floats up to 12 volts. When the pin at the computer goes negative, that means the computer is turning the element on, having 0 volts on one side, and 12 volts on the other(the constant feed 12 volts).
Thread Starter
|
New User
Joined: Sep 2003
Posts: 4
Likes: 0
Pin 95 seems to ground after a minute or two, where as pin 93 which is the ground for the other sensor grounds the second I start the engine. Pin 95 is delayed. I think this is why I am getting the code P135.
need help
Thank you
need help
Thank you
Moderator
Joined: Jan 2001
Posts: 56,997
Likes: 2,743
From: Virginia
I looked up p135 and it is a o2 heater circuit malfunction(of course you knew this already?). I would check the wiring carefully, especially if you had any exhaust work done recently. Have you tried replacing the sensor?
Thread
Thread Starter
Forum
Replies
Last Post
blue84f250
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
11
May 19, 2013 11:23 PM
