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This DIY describes how to test the ground connection and fuel pump relay for excess resistance. Excess resistance at these places can cause a variety of electrical faults as the voltage available to the electronics in the car drops. Many people report the ABS light to be the first symptom of low voltage.

The 2.0 has the unusual feature of PCV heating element that can be used to good advantage for this test. It is conveniently located, the voltage supply for it comes through the fuel pump relay and it uses the same ground connections as the ECU. You will need a digital volt meter for this test.

The first step is to remove the connector for the PCV heating element which is located just behind the oil cap. There is a latch on the back of the connector. Push up and squeeze in the location and direction indicated by the arrow:

Vehicle Auto part Car Engine Fuel line

With the parking brake on, start the engine and let it idle in neutral. Touch the meter probes to the terminals in the connector. The round end of the connector shell indicates the positive side (labeled “1”) and the flat end indicates the negative side (labeled “2”). (You don’t need to worry about which meter lead you connect to which terminal. If it is reversed you will get a negative voltage, but just ignore the sign.) I measured 13.99 volts.

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Measuring instrument Tool Gauge Finger Impact driver

Next go to the battery and check the voltage there. Here I have touched the probes to the battery positive terminal (labeled “3”) and negative terminal (labeled “4”). Notice that I am touching the leads to the battery terminals themselves to get the most accurate reading. The nut that I have circled is for the connection from the battery to all the electrical systems of the car. The connection needs to be clean and secure.

Tool Measuring instrument Wire Gas detector

With a good battery and charging system you should get between 14.0 and 14.5 volts. Here I measured 14.17 volts. The 0.18 volt difference between my readings is the voltage drop due to the losses in the circuit, mainly the fuel pump relay contacts and the ground connections. To figure out which it is measure the voltage between the PCV heater connector and the battery as shown here:

Automotive battery Auto part Wire Engine Electrical wiring

Measure between the following pairs of contacts as labeled in the pictures above:
A) Point 1 to point 3 to check the fuel pump relay.
B) Point 2 and point 4 with the headlights on and climate control fan on high to check the ground connection. (The headlights and fan put an extra load on the ground connection.)
I measured 0.12 volts for A) and 0.01 volts for B). Finally, if you measure a large voltage for A) there is one last check which is the loss through the battery-top fuse panel. Measure from the battery positive terminal (“3”) to the cable second from the left (when standing in front of the car) going out from the fuse panel, labeled “5” below:

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I measured <0.01 volts, so my 0.12 volt drop is all at the fuel pump relay. I’m not aware of any specs for these voltage drops but I think 0.2-0.3 for the relay and 0.1 for the ground connection is acceptable. For the fuse panel it should be under 0.01 volts.
 

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Nice info.:goodjob::goodjob:

This DIY describes how to test the ground connection and fuel pump relay for excess resistance.

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The 2.0 has the unusual feature of PCV heating element that can be used to good advantage for this test.
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Does someone know how to do this for 1.8T engine?? :confused:
 
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