SL/R129: 94 SL320 top, windows, roll bar stopped working
Thank-you
Last edited by GibbyMN; Aug 29, 2016 at 01:17 PM.
Each system's diagnostic output signal is wired to a specific socket of the car's main "diagnostic connector", X11/4. Early cars with continuous-fuel injection have 16 sockets, while later models have 38 sockets (picture). The sockets are numbered for easy identification. When you make connections to any of the you should know that all circuits have protected outputs and nothing can be damaged by mistakes.
On a car manufactured in '04 the socket for the convertible top is #21. The socket for the roll bar is #22.
Codes are read sequentially one at a time. That is, you trigger the system you are checking to issue a code, you read the code, you trigger another code, and so on. With the key on and engine off, you trigger a code by electrically shorting the system's particular diagnostic socket to ground for 2 to 4 seconds using a wire. A second or two after the wire is removed, a series of electrical pulses will occur at the socket. The number of pulses corresponds to the number of a code.
There are numerous ways to view the pulses for counting and getting codes. The voltage of the pulses is roughly 12-volts DC. I connect a 12-volt LED and watch it flash. A test lamp or multimeter can work as well.
The codes you read may indicate current problems, or they may indicate a problem that existed long ago and has since gone away. Therefore, you want to erase a code immediately after reading it. To erase a code you short the diagnostic socket to ground for 6 to 8 seconds. Once all codes are erased, attempt to operate the top and roll bar and see what fresh codes appear.
Last edited by bobterry99; Sep 3, 2016 at 08:12 PM.
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