Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1994F 150 2WD PICKUP L6-300 4.9LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSTESTING AND INSPECTIONPINPOINT TESTSX - CONSTANT CONTROL RELAY MODULE (CCRM)X - TESTING NOTES
1994 Ford F 150 2WD Pickup L6-300 4.9L
X - Testing Notes
1994 Ford F 150 2WD Pickup L6-300 4.9LSECTION X - Testing Notes
DESCRIPTION
Constant Control Relay Module
The Constant Control Relay Module (CCRM) interfaces with the Electronic Engine Controls (EEC) system to provide control for the cooling fan, A/C clutch and the fuel pump. The CCRM also contains the EEC power relay which provides Vehicle Battery Power (VPWR) to the Powertrain Control Module (PCM) and EEC-IV system.
Dual and Single Function A/C Pressure Switch (ACPSW)
The ACPSW is used on some applications for additional A/C system pressure control and is also known as the refrigerant containment switch. The normally open medium pressure contacts close at a predetermined A/C head pressure. This grounds the input to the PCM indicating that the high speed cooling fan is required. The normally closed high pressure contracts are used on all CCRM applications and open at a predetermined A/C head pressure. This turns off the A/C by opening the A/C demand circuit preventing the A/C pressure from rising to a level that would open the A/C high pressure relief valve. For additional information, refer to Heating and Air Conditioning.
NOTE: You should enter this Pinpoint Test only when directed here from Diagnostic Routines, or from Pinpoint Tests C, PA, or PB.
REMEMBER: To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault:
- Fuel system
- A/C system
- Fuel Contamination
- Starting/charging system
This Pinpoint Test is intended to diagnose only the following:
- Constant Control Relay Module (CCRM).
- Electronic Engine Controls (EEC) Power Relay
- Low Fan Control (LFC) Relay
- High Fan Control (HFC) Relay
- Wide Open Throttle A/C Cut-Off (WAC) Relay
- Fuel Pump (FP)
- Pusher Fan Control Relay
- Harness circuits: B+, KPWR, PWR GND, FP, LFP, HFP, FC, LFC, HFC, PFC, A/C, ACCS, ACPSW, WAC
- Powertrain Control Module (PCM) (12A650)
Constant Control Relay Module
The Constant Control Relay Module (CCRM) interfaces with the Electronic Engine Controls (EEC) system to provide control for the cooling fan, A/C clutch and the fuel pump. The CCRM also contains the EEC power relay which provides Vehicle Battery Power (VPWR) to the Powertrain Control Module (PCM) and EEC-IV system.
ACPSW Switch:
Dual and Single Function A/C Pressure Switch (ACPSW)
The ACPSW is used on some applications for additional A/C system pressure control and is also known as the refrigerant containment switch. The normally open medium pressure contacts close at a predetermined A/C head pressure. This grounds the input to the PCM indicating that the high speed cooling fan is required. The normally closed high pressure contracts are used on all CCRM applications and open at a predetermined A/C head pressure. This turns off the A/C by opening the A/C demand circuit preventing the A/C pressure from rising to a level that would open the A/C high pressure relief valve. For additional information, refer to Heating and Air Conditioning.
NOTE: You should enter this Pinpoint Test only when directed here from Diagnostic Routines, or from Pinpoint Tests C, PA, or PB.
REMEMBER: To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault:
- Fuel system
- A/C system
- Fuel Contamination
- Starting/charging system
This Pinpoint Test is intended to diagnose only the following:
- Constant Control Relay Module (CCRM).
- Electronic Engine Controls (EEC) Power Relay
- Low Fan Control (LFC) Relay
- High Fan Control (HFC) Relay
- Wide Open Throttle A/C Cut-Off (WAC) Relay
- Fuel Pump (FP)
- Pusher Fan Control Relay
- Harness circuits: B+, KPWR, PWR GND, FP, LFP, HFP, FC, LFC, HFC, PFC, A/C, ACCS, ACPSW, WAC
- Powertrain Control Module (PCM) (12A650)
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.