1979-1993 & 94 Conv [Subscribe to Daily Digest] |
Hi Claudia!
Sorry you are having issues. But you did great giving us the symptom!
Four flashes means the LH system is not receiving it's signals from the Knock Sensor. There are four possible reason:
1) the connector is disconnected or has an internal open.
2) the sensor has failed.
3) the sensor to block contact is dirty.
4) the sensor orientation is incorrect.
By a wild coincedence, I just repaired two of them, one the knock sensor was *melted* and the other one of the contacts in the connector had pulled back in the shell and was not making contact.
The good news is you should not be hurting the car, it will be running in a dimished mode.
Where is the sensor? If you open the hood and stand on the left side of the car facing the engine (like you were going to check oil) you will see the four intake tubes from the intake plenum to the top of the block on the engine. Between the middle two is a black plastic sensor about diameter of a quarter (you will have to lean over and look straight down between the tubes), but in has a silver 12 mm bolt right through the middle of it. It has a connector plugged into it and that wire goes toward the distributor.
The checkpoints are 1) does it look like it got melted? 2) is the connector on the sensor pointed towards the left from headlight? (orientation is important) 3) depending upon where you live you can get the aluminum crud growing in the metal, a clean connection is required for proper operation 4) does it look like the connector is clean and intact.
If nothing is obvious, I would remove the knock sensor, check the inside of the connector, clean the sensor contact surface, and clean the contact surface on the block.
Tools needed:
12mm socket on 8" or longer extention and ratchet 3/8" drive
a piece of tape, any but scotch - 3m blue, duct tape, paper tape, masking tape
a magnet on an extension to move things around
a long screwdriver to help reposition the sensor upon reinstall
small piece of sand paper
small screwdriver like the ones with a pocket clip on the handle
Black Plastic tape
Single sided razor blade or hobby knife
using the socket, remove the 12 mm bolt in the middle of the sensor, extract bolt with magnet
the wire on the sensor can be eased out towards the front bumper somewhat under the AIC
now you should have enough slack to open the connector, press the wire to unlock the connector.
Take the sensor and either use 400 grit sandpaper or the floor of a smooth concrete garage. In either case, put the round metal portion on the abrasive surface and do the infinity sign (figure eight but laid on the side). do a couple and look at the metal, it should be getting clean and maybe shiny too.
Take a piece of sandpaper and fold and wrap around the end of the socket extention bar. poke it down in the place were the sensor mounted, move around and work to get the portion that sensor clean, renew sandpaper as necessary.
Look at the two receivers in the connector, are they at the same depth? If not you will need to work from the other end of the connector to push the short one back to the level of the other. the boot on the shell made, ok will, disintegrate as you try to remove it. you can use black tape later, small screwdriver to push connector back into shell. secure with black tape. plug back into sensor, remove and recheck position of connections, do it again.
Snake the wire with the sensor plugged into it back where it came from.
put the shouldered bolt back into the socket, use a little tape on the side of the socket to cover just a little of the bolt shoulder to keep it in the socket while you get it started.
use the magnet, long screwdrive, and whatever you need to position the knock sensor back in place, use the screwdriver to help fine tune position while you put the bolt thru the sensor and get the bolt started.
The contact surface forces you to point the sensor towards the left headlight, it will be very difficult to start the bolt if the sensor is not pointed that way. With correct orientation of the sensor start the socket to tighten, use the screw driver against the other side of the sensor to prevent it from rotating towards the right.
Snug it down and step back and admire the job well done. Clear all of the tools away from the area, and go for a test drive.
let us know how you fare!
, Tue, 19 Sep 2006 20:24:44
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