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A few weeks ago, I was having trouble with the check engine light. Naturally, when I took it to the shop everything worked and they said that they couldn't find anything. I bought an Actron code reader and pulled the following codes:
18 -
loss of TACH signal to ECA;
DIS fault - primary circuit faliure in coil pack 1,2,3 or 4;
Electronic EDIS fault - failure in SAW circuit.
After I pulled the codes I checked the coil pack. Low and behold one was not connected securely. I also noticed a hardened substance (probably from the grease in the spark plug boot). I cleaned all the boots (4) and regreased them. It started and ran like a charm for 1 day before the light came back on.
Question:
What's next?
And IF I have to take it in to a shop (which is very possible) what should I expect them to tell me. OR do you think that a novice/enthusiast like me can get the job done?
P.S. Has it been any of your experiences that a code 18 can cause my engine to fail?
Pull the codes again, it might not be the same code being thrown.
DTC 18/212 indicates a loss of IDM input to the PCM.
Possible Causes:
-- Open harness circuit.
-- Shorted harness circuit.
-- Damaged Ignition Control Module (ICM).
-- Damaged Powertrain Control Module (PCM).
The IDM signal is sent from the DIS Module to the PCM when a coil fires, the circuit runs between the two components.
Based on the above, you have either (1) a short or open in the wiring between the PCM and DIS Module, (2) the DIS Module itself is bad, or (3) the PCM is bad. Nos. 1 and 2 are more likely.
Here is a diagram of a typical DIS system showing the relationship of the IDM circuit to the rest of the ignition components, it's for a 6 cylinder but the systems are identical otherwise: