Testing CCRM

[Pistoleye]

My shop manual says to take it to a dealer to test, I am just wondering if there is a way to test it at home? I am having some fuel pump problems, there is power going to the relay but at the fuel pump it seems a little low. At first I thought that any power to the pump would mean that the relay is working but now I am secound guessing everything....any Ideas? Its a 95 GT

 

[HISSIN50]

How much lower is the voltage at the CCRM vs the pump? A bit of voltage drop is normal (it should be less than 1/2 volt).

Good luck.

 

[Pistoleye]

Its only about 4 volts at the pump, think the other 8 volts are eaten up by a bad CCRM?

 

[mo_dingo]

Its only about 4 volts at the pump, think the other 8 volts are eaten up by a bad CCRM?

Yeah that's really bad. You definately have a nasty voltage drop.

Start with this. The CCRM gets power on what looks like 2 different sources. There is a yellow wire at the ccrm which comes from the EEC fuse (hot all the time). Another yellow wire feeds the ccrm, and another comes from the fuel pump fuse. You need to test the voltage on the fuel pump one, and the eec fuse one. See if you see at least 12V. If it's lower, you have a wiring problem before the ccrm.

There is another lead, Red/lt. green, that is hot with ignition only. I assume this just activates the ccrm, but you should test it as well.

If the voltage going into the ccrm is low, the output will be low as well. The output wire to the fuel pump is Dark green/yellow. Check it there as well.
Scott

 

[HISSIN50]

To add to Scott's post with some numbers: have you checked CCRM pins 5 vs 11? 5 is power from the relay to the pump and 11 is twelve-volts from the battery (common terminal on the FP relay).

If 5 is low, you know the issue is up front. If 5 is high, that indicates the CCRM is ok and the issue lies in the rest of the circuit (downstream). Checking both sides of the inertia switch voltage might be useful at that point.

Good luck.

 

[mo_dingo]

To add to Scott's post with some numbers: have you checked CCRM pins 5 vs 11? 5 is power from the relay to the pump and 11 is twelve-volts from the battery (common terminal on the FP relay).

If 5 is low, you know the issue is up front. If 5 is high, that indicates the CCRM is ok and the issue lies in the rest of the circuit (downstream). Checking both sides of the inertia switch voltage might be useful at that point.

Good luck.

Do you have a pinout for the ccrm??? that would be awesome if you would share!!!!!

 

[braxx]

Mustang
Pin Circuit Wire Color Application Abbreviation
1 260 R/O Power to Cooling Fan (Low Speed) PTF
2 260 R/O Power to Cooling Fan (Low Speed) PTF
3 38 BK/O B (+) to Fan Relay B (+)
4 38 BK/O B (+) to Fan Relay B (+)
5 238 DG/Y Power to Fuel Pump PTP
6 261 O/BK Power to Cooling Fan (High Speed) PTF
7 261 O/BK Power to Cooling Fan (High Speed) PTF
8 37 Y B(+) to EEC Power Relay B(+)
10 37 Y B(+) to EEC Power Relay B(+)
11 37 Y B(+) to Fuel Pump Relay B(+)
12 361 R Vehicle Power VPWR
13 16 R/LG Ignition Start/Run IGN
14 228 DB Low Speed Fan Control LFC
15 570 BK/W Power Ground PWR GND
16 57 BK A/C Clutch Ground PWR GND
17 639 LG/P High Speed Fan Control HFC
18 926 LB/O Fuel Pump Circuit FP
21 198 DG/O A/C Cycling Switch ACCS
22 331 PK/Y Wide Open Throttle A/C Cut-Off WAC
23 347 BK/Y Power to A/C Clutch Coil PTAC
24 361 R Vehicle Power VPWR

 

[braxx]

Here is a schematic:

 

[Pistoleye]

Thanks braxx!! I am still a little lost, I am getting about 7 volts at the #11 and # 5 pins without the ignition on?? I think I have a bad battery or multimeter, but should there be voltage with out the key on?

 

[mo_dingo]

Thanks braxx!! I am still a little lost, I am getting about 7 volts at the #11 and # 5 pins without the ignition on?? I think I have a bad battery or multimeter, but should there be voltage with out the key on?

No, you should see voltage at pin 11 all the time. It should be the same as battery voltage. If it isn't, you need to run a new wire from the battery to pin 11 at the ccrm.

IDK what you should see at pin 5 though. From the diagram, it looks as if it gets 12v+ from the battery through the fuel pump relay (when activated), but it also gets ground from pin 15 which hooks to ground at the battery. It has a diode in series from the ground line but that shouldn't have an effect.

Start with pin 11. Compare the voltage from the battery and to pin 11. They should be the same. if not, you have a bad wire/connection somewhere, is my assumption.
Scott

 

[Pistoleye]

Thats the strange part the voltage is the same at pin 5 and 11 as the battery with ignition off, but then the fuel pump would be on all the time? no?

 

[mo_dingo]

Thats the strange part the voltage is the same at pin 5 and 11 as the battery with ignition off, but then the fuel pump would be on all the time? no?

yeah that should be the case. but since it's so low, who knows what's going to happen......

 

[Pistoleye]

Ok so I tested one of the wrong pins, now when testing pin#5 I get a blip on the meter when the ignition is on (1/2 a volt or so) I guess it must be the relay... Thanks for the help!

 

[HISSIN50]

I take it all the other relays in the CCRM work (it's not an issue with the relay coil)?

It's expensive to swap CCRM's, so be careful and test twice (like the old addage, measure twice, cut once). Pay real attention to the numbers and interchange info with said CCRM because I've seen conflicting lists out there.

Good luck.