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Discussion Starter · #1 ·
when I short the ALDL diagnostic link to earth to show codes the radiator cooling fan comes on as well.
Any idea's ????
 

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when I short the ALDL diagnostic link to earth to show codes the radiator cooling fan comes on as well.
Any idea's ????
Nope, no ideas as that's exactly what it is supposed to do. When in diagnostic mode, the ECM will energize virtually every relay under its control, including the Main Fan Relay.
 

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Discussion Starter · #3 ·
Thanks for response
Also when you turn ignition on the fuel pump does not energise for 2 sec's ,is that controlled by ECM ?
 

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Thanks for response
Also when you turn ignition on the fuel pump does not energise for 2 sec's ,is that controlled by ECM ?
The ECM will send an energize signal (Battery Voltage) to the Fuel Pump Relay. If the Fuel Pump does not run during these two seconds, the Fuel Pump Relay may be at fault.

Why not just precisely state the problem you are having. Many smart folks on here that can point you in the right direction.
 

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Discussion Starter · #5 ·
Having a few problems not just one.
The car runs once it starts. Tested fuel pump relay thats ok, just not the 2 sec's when ignition is turned on.
 

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Tested fuel pump relay thats ok, just not the 2 sec's when ignition is turned on.
How did you test the relay? Looking at the schematic:

The ECM should output battery voltage to pin C (Green/White wire) of the relay for two seconds when switching ignition on. After two seconds, if the ECM is not receiving reference pulses from the distributor (engine not turning), the ECM removes this battery voltage on pin C. Just cycling the ignition off and then back on will not restart this prime cycle. You need to switch the ignition off for at least 15 seconds (I wait 30) before the prime cycle will happen again.

The Fuel Pump Relay and priming is sort of academic really as if the Oil Pressure Switch is working, it will bypass the relay and energize the Fuel Pump after cranking brings up oil pressure to above ~4psi. This causes extended cranking before startup, but it does work. I keep my battery fully charged when not in use and my car builds oil pressure quickly. I ran my car for a week with the Fuel Pump Relay removed while waiting for a replacement and hardly noticed the difference.

First check that all ECM fuses are good. Don't just look at them, Ohm them out. Next, leave the ignition off, pull the Fuel Pump Relay, connect a volt meter or test light between the relay connector pins E (Orange) and B (Black/White). Test light should light or you should see battery voltage on the meter. If not move the probe from pin B to a good chassis or engine ground point. If this works, check the ground on the black/white wire at pin B. Assuming the E to B test was good, connect tester to pins C (Green/White) and B, wait 30 seconds and switch ignition to ON. If no light on test light or no battery voltage on meter, you need to trace back the green/white wire to the ECM.
 

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Discussion Starter · #7 ·
Tested fuel pump relay by putting 12v to aldl terminal for f/pump

Will do your checks over weekend.
Thanks for info
 

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Tested fuel pump relay by putting 12v to aldl terminal for f/pump
This test is mainly for the Fuel Pump as it passes through the Normally Closed contacts of the Fuel Pump Relay. Once the ECM energizes the relay, these contact open and the Normally Open contacts close. Your test didn't test if the relay can energize or if it does, if the NO contacts are good. These relays are cheap enough to have one for the toolbox as the fastest method of troubleshooting this is by substitution. Post back how you make out with the checks.
 
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