Key on voltage drain '94 Cobra

[glittle75]

94 cobra, newer (less than a year) battery and alt.

Measuring with a Fluke

With key off battery is at, or slightly above, 12v. Key in acc, radio comes on, etc. battery hovers around 12v.

Key on, engine off. Battery drops immediately to 4.7-4.8v, and slowly drains lower, key off, back to 12v.

Disconnecting the CCRM, no drain. This is leading me to check the things the CCRM controls.

I am also reading around and seeing people have had to mess with the GEM wires, etc. So basically I am looking for any advice for other things to check that you guys have seen or read relating to a massive key on drain. Planning to check the fuel pump, starter, etc in the morning.
Also, will the CCRM out of my Mach (2003) work to swap and prove a new CCRM is in order? The ford PN's are different, but the cars are 10 years apart, and I cant find anything saying they do or do not interchange. Asking because I do not want to burn the Mach's CCRM up if they are not interchangable.

 

[2DXTRM]

The CCRM from your Mach 1 wont work.
A CCRM from a 94-00 Mustang will work.

Some CCRM diagnostics explained in this link:
http://www.accutach.com/Documents/Anatomy of a 96 Mustang CCRM-R1.pdf



Also from elsewhere on the web:

Some EEC relay diagnostics: If it seems like none of the EEC systems are receiving power (underhood solenoids, fuel injectors, etc), here’s a place to look. First check the PCM/CCRM fuse in the underhood fuse box (20 amps). Also check the ignition switch fuses.
At the CCRM (Constant Control Relay Module – the black box mounted on the radiator overflow bracket): With the key turned to run, check Pin 12 and 24 for accessory power. If it’s there, the issue lies past the CCRM. If there’s no power: Check CCRM Pins 8 and 10 for constant 12 volts. Check CCRM Pin 13 for accessory 12 volts. Check CCRM Pin 15 for ground. If 8, 10, 13 and 15 are present (this requires the key to be on), but 12 and 24 are not showing 12 volts, that suggests a bad EEC relay inside the CCRM.


Fuel pump relay diagnostics: First, always check the inertia switch in the trunk and the fuel pump fuse in the underhood fuse box (20 amps). Also check the ignition switch fuses. With the key turned to run and checking within the fuel pump prime-out period (a duration of 2-5 seconds after turning the key to run): Check CCRM pin 5 for accessory 12 volts. If you have it, the issue lies downstream. If not: Check CCRM Pin 11 for constant 12 volts. Check CCRM Pin 13 for accessory 12 volts. Check CCRM Pin 18 for a ground signal during the prime-out.
If this is all good, check the inertia switch (located in the driver side trunk, adjacent the tail light) and fuel pump electrical connector at the tank.

Fan relay diagnostics (EDF and HEDF): Low speed fan relay diagnostics (the fan circuit is rather broad given the EDF module), so only relay ins/outs are noted here:
If low speed isn’t coming on, but you are getting 12 volts to CCRM Pin 14 at or greater than 208*F and the fuses are intact: With the key on, check CCRM Pins 1 and 2 for twelve volts when the fan should be on. If there’s not 12 volts: Check Pin 15 for ground. Check pins 3 and 4 for constant 12 volts.
If high speed doesn’t come on at ~228F or with the A/C turned on, but CCRM Pin 17 shows continuity to ground: With the key-on, check CCRM pins 6 and 7 for 12 volts when the high speed fan should be on. Check Pins 3 and 4 for constant 12 volts. Check Pin 13 for key-on 12 volts.

Some diagrams: