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kansaschity · Nov 21, 2009, 11:05 AM

If a main relay is bad, is it possible to still hear all three clicks?

After driving around just fine, I came home and parked the car. The next morning it would not start. Ive had a no start problem a couple times before like when running into a gas station then back out. Obvious sign of a main relay problem, but its been quit a while since its done that.

No codes, cel comes on for a few seconds then goes off as normal but I don't hear the fuel pump prime during this period. Listened/felt the main relay, makes all 3 clicks as normal and joints don't appear to be in bad condition. I checked all fuses. ECU fuse was blown, replaced it, still no start. Sanded down the ground on the thermostat to get a good connection, fuel pump still won't prime. Is there any other grounds to check for the fuel pump, and would a bad ecu stop it from priming?

TxGreaseMonkey · Nov 21, 2009, 11:58 AM

. Test all under dash and under hood fuses with a test light or multimeter:

https://www.askmehelpdesk.com/cars-t...tml#post252145

Be very thorough, since it will save a lot of time and money.

. Perform the K-Test on the ECM:

Remove the MAP Sensor connector and turn the ignition switch to ON (Position II). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it's probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.

. Replace the main relay, if the problem persists. I recommend replacing the main relays every 120,000 miles or 10 years, whichever comes first.