DTC P0526 Cooling Fan Speed Sensor Circuit
Circuit Description
The powertrain control module (PCM) uses the cooling fan speed signal in order to determine the actual fan speed in relation to the desired fan speed. The PCM uses the cooling fan speed signal in order to reduce the cooling fan noise and in order to maintain the powertrain cooling requirements. The PCM supplies power and ground to the clutch hall effect sensor of the cooling fan clutch. The hall effect sensor returns a signal pulse through the speed signal circuit in response to the reluctor track, which is located inside the fan clutch. If during operation, the PCM detects a loss of the cooling fan speed signal, DTC P0526 will set.
Do you know how to test electrical circuit's ?
Diagnostic Aids
• An inline connector could cause an intermittent DTC. Ensure to test for poor connections and pin retention at all inline connectors. Refer to system schematics for connectors and locations.
• If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections .
• Disconnect the harness connector of the cooling fan clutch from the shroud. Inspect the exposed wires between the harness connector and the tubing.
• Inspect the cooling fan clutch harness in order to ensure that the clutch supply voltage circuit is not shorted to the following circuits:
- The 5-volt reference circuit
- The cooling fan speed signal circuit
- The low reference circuit
• DTC P0526 will set if the engine is started without the drive belt ON.
Connector End View Reference: Cooling System Connector End Views
1
Did you perform the Diagnostic System Check - Vehicle?
--
Go to Step 2
Go to Diagnostic System Check - Vehicle
2
Turn OFF the ignition.
Disconnect the cooling fan clutch harness connector at the shroud.
Connect a jumper wire between each of the following circuits:
• The 5-volt reference circuit
• The cooling fan speed signal circuit
• The low reference circuit
Measure the voltage of the cooling fan speed sensor circuit and a good ground.
Turn ON the ignition, with the engine OFF.
Manually rotate the cooling fan clutch.
Does the voltage change from 0 to 5 volts?
0-5 V
YES - Go to Step 9
NO - Go to Step 3
3
Disconnect the jumper wires.
Measure the voltage between the 5-volt reference circuit and the low reference circuit of the cooling fan clutch.
Is the voltage measurement near than the specified value?
5 V
YES - Go to Step 6
NO - Go to Step 4
4
Turn OFF the ignition.
Probe the low reference circuit of the cooling fan clutch with a test lamp connected to battery positive voltage.
Does the test lamp illuminate?
--
YES - Go to Step 5
NO - Go to Step 8
5
Test the 5-volt reference circuit of the cooling fan clutch for a high resistance, or for an open. Refer to Circuit Testing and to Wiring Repairs .
Did you find and correct the condition?
--
YES - Go to Step 14
NO - Go to Step 6
6
Test the cooling fan speed signal circuit of the cooling fan clutch for a short to ground, for a high resistance, or for an open. Refer to Circuit Testing and to Wiring Repairs .
Did you find and correct the condition?
--
YES - Go to Step 14
NO - Go to Step 7
7
Test the cooling fan speed signal circuit of the cooling fan clutch for a short to voltage. Refer to Circuit Testing and to Wiring Repairs .
Did you find and correct the condition?
--
YES - Go to Step 14
NO - Go to Step 10
8
Test the low reference circuit of the cooling fan clutch for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs .
Did you find and correct the condition?
--
YES - Go to Step 14
NO - Go to Step 11
9
Disconnect the jumper wires.
Test the cooling fan speed signal circuit of the cooling fan clutch for an open. Refer to Circuit Testing and to Wiring Repairs .
Did you find and correct the condition?
--
YES - Go to Step 14
NO - Go to Step 11
10
Inspect for a poor connection at the harness connector of the cooling fan clutch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .
Did you find and correct the condition?
--
Go to Step 14
Go to Step 12
11
Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs .
Did you find and correct the condition?
--
Go to Step 14
Go to Step 13
12
Replace the cooling fan clutch. Refer to Fan Clutch Replacement .
Did you complete the replacement?
--
Go to Step 14
--
13
Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
--
Go to Step 14
--
14
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running in the DTC.
Does the DTC reset?
--
Go to Step 2
System OK
You'll need wiring diagram so you know which wires to test . Free diagrams here at http://www.bbbind.com/free-tsb/
Enter vehicle info. year , make model an engine . Under system click on engine then under subsystem click on cooling fans . Click the searc button then the blue link.
×
Subject:
Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set, No Communication with TCCM (Reprogram Transfer Case Control Module)
Models:
2004 Buick Rainier
2002-2004 Chevrolet TrailBlazer, TrailBlazer EXT
2003-2004 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2002-2004 GMC Envoy, Envoy XL
2003-2004 GMC Sierra, Yukon, Yukon XL
2004 GMC Envoy XUV
2002-2004 Oldsmobile Bravada
with Electronic Shift or Active Transfer Case (RPOs NP1, NP4 or NP8)876 views
Usually answered in minutes!
×