Knock sensor diagnosis (Scirocco 16v only)- To display faults stored
in memory:
1. Connect an LED test light between the test connector (up by throttle
body on top) and + battery terminal.
2. Switch the ignition on, - the test light should go on.
3. Start the engine - the test light should go out (a slight glow is
ok)
4. Briefly raise the engine speed to at least 3000 rpm. If the
test light comes on again, proceed with the next step. If not, there
are no faults stored in memory.
5. With the engine idling and the test light connected, use a jumper
wire to ground the test connector for at least 3 sec.
Note - Do not switch the ignition off during this step. Doing so will permanently erase the fault memory.
Series of 2 flashes indicate a fault in the wiring harness, the knock
sensor, or the knock sensor control unit. Loosen and retighten the
knock sensor using the proper tightening torque.
Series of 3 flashes indicate a problem with the vacuum connection to
the knock sensor control unit. Check vacuum hose for kinks or damage,
replace if necessary. If the vacuum hose and hose connections are
OK, the knock sensor control unit is faulty and should be replaced.
Hope this helps... Let me know if you need more info.
Sal Guzzo wrote:
I wasa thinkin', how do I check to see if the knock sensor box and the O2--
sensor box are working? I attempted to start the 81 rocco 16V with a
battery starter and she spin nicely. Unfortunately, it didn't even wanna
backfire. Disappointment crossed my path but I'm sure that it'll eventually
start. I'll try adjusting the air flow path and if nada results, it's off
to Motronix!!!!