grey wire connecting to purple wire on ign module

[eagle87]

just wondering what does the grey wire that connects the the purple one on the ign module do? only one of my 87 eagles have this for some reason

[carnuck]

IIRC, it was for high altitude

[BenM]

The Purple/Orange pair sometimes is connected to the Hall-Effect sensor on the distributor.

With the ECM starting in 1983 it provides a signal to the ICM on one of the wires. The wiring diagram I have shows the orange wire hooked up to the ECM, but either way if it works, it works. The other wire is just power I believe.

When the ECM is used, it connects to the Hall sensor and sends a modified signal to the ICM on it's sense wire, the ECM doesn't need power.

Without the ECM, the purple/orange pair connects to the sensor directly. The sensor has no polarity, so it doesn't care which wire is which. The ECM and ICM do.

1982 (The Concord DL in your sig) should have a yellow grommet ICM with three plugs. The ECM uses the third plug to control the ICM instead of sitting in the middle and pretending to be the sensor.

[eagle87]

i think carnuck might be closer to what the wire is, what confuses me is why this particular eagle would have it, as it was sold in ontario canada which isnt high altitude

[eagle87]

all other eagles ive seen only use 3 of the wires off the ign module and the 4th is just plugged, is the 4th one this one has the high alt wire then?

[BenM]

Do you mean on these connectors?

[carnuck]

http://www.partsgeek.com/assets/dimage/full/1200150.jpg 3 plug module?

[eagle87]

mines a 2 plug 1988 style with the gm style weather pack connectors, as this is a late 87,  one plug has 2 wires the other 4, however normally the 4th purple wire isnt used on the harness side (as it is on my other 2 87's)

[BenM]

Ok. Possibly someone tried to bypass MCU control of the ignition.

Have you seen the mixture pins move in the carb?

How about other signs the MCU is working?

[eagle87]

ill dig in the harness more, however this wire appears to be factory (you can see where it had broken off at the plug and had been rejoined), and all the sensors are intact, had feedback carb on it, i temporarily have a non feedback on it

[eagle87]

had a closer look at my other 87 and figured out what that wire is supposed to be for! Its the a/c clutch wire grey with black tracer and for some reason a previous owner reconnected it to the ign module (this car never had a/c so it wouldve been just an extra wire) guess they assumed it was ignition related, ill disconnect it from the module since it doesnt do anything! Lol

[BenM]

Wow, never would have guessed that!

[carnuck]

So it's to kick the RPM up when the AC kicks in?

[eagle87]

its the wire that would normally go to the a/c clutch, some wires had melted at the solenoid and i guess they thought it was ignition related since it didnt go anywhere since this car has no a/c