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K. Wiggins
K. Wiggins, ASE Certified Technician
Category: Car
Satisfied Customers: 2998
Experience:  ASE Certified Technician, Associates Degree in Automotive Technology, 15+ years in the trade
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Chevrolet Tracker 4x4: 2003 Chev Tracker, 4 cyl, 103k miles.

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2003 Chev Tracker, 4 cyl, 103k miles. Just had alternator replaced. Drive home, turn off car and top relay (of two), under dash to the left of the steering wheel, near kick panel starts buzzing. Turn engine on, problem goes away. Turn off, starts buzzing. Lift hand brake, buzzing goes away for short while, but returns. Pull out relay, car will not start. Put relay back in, car starts fine - but above still prevails...

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Does this vehicle have an aftermarket alarm or remote start kit? When reviewing the wiring schematics there are no relays that would inhibit starting.

Customer: replied 5 years ago.
No aftermarket systems that I am aware of. My mechanic is stymied by this as well. As he says, " must be a 'top secret' relay..." as he can not find it in any of the system specs or in the owner's manual. The relay appears to be original to the car as it is at the end of the fuse block that is inside the car next to the driver kick panel under the dash. With relay out, starter motor cranks but no ignition. Relay in, car starts fine and all systems are working. Turn off car and in a few seconds relay starts to, I guess best description - cycle rapidly - which causes it to vibrate and buzz loudly. I am referring to it now as the Relay from Hell. Both my mechanic and think it is an open ground - any help identifying the circuit this relay is on would be terrific.
Found it. They are the main and fuel pump relays. I'll post wiring diagram so you guys can check things out. If you need more assistance just let me know.

Customer: replied 5 years ago.
Yes, I found a schematic online last night that shows the main relay as the top and the fuel pump as the bottom relay. So now the big question, what might be causing that relay to open and close rapidly after the ignition is shut off (thus vibrating and buzzing loudly). What is on that circuit where we can look for a short. It sounds like an open ground. Would the changing of the Alternator have anything to do with it? I'm still with you on this....
I will look at the diagrams and post momentarily
Looking at the schematic heres how I would suggest testing the grounds.

The ecm controls these relays via ground. When the key is turn on the ECM ground the main relay to give power to the fuel pump relay and to send power to the injectors. The fuel pump relay is activated via the ecm supplying ground when it sees input from the oil pressure switch/crank sensor.

Testing wires for short to ground;

I would suggest testing for continuity between the wire at the relay and its corresponding pin at the ecm connector there should be continuity. If that checks there is no short to ground in the wiring harness and you need to check for ground on that terminal with both the key off and key on.

Testing main relay;

The main relay should only have ground when the key is on. Using ohm meter connect one probe to ground and the other probe to blue wire (pin 5) at the main relay connector. It should have no continuity to ground with the key off. If it pulses between continuity/no continuity the ecm is bad.

Testing fuel pump relay;

Ground should only be present on the white/green wire (pin 5) on the fuel pump relay for 3 to 5 seconds when key is first turned on, then constant when engine is cranking. If wire has ground at any time with key off and wiring has been confirmed to not be shorted to ground as in our first test the ecm is again suspect.

If I can assist further, please, let me know.
K. Wiggins, ASE Certified Technician
Category: Car
Satisfied Customers: 2998
Experience: ASE Certified Technician, Associates Degree in Automotive Technology, 15+ years in the trade
K. Wiggins and 2 other Car Specialists are ready to help you
Customer: replied 5 years ago.
My mechanic informed me that he found corrosion at the ground wire to the engine block (or somewhere there abouts). He cleaned and reconnected and problem seems to be resolved. More testing tomorrow morning when I go back for the car. I think that is in line with what you told me here. You did very thorough work here. Many thanks.
You are very welcome. I am not pleased until your vehicle is fixed. Hope you have a wonderful week end.
Customer: replied 5 years ago.
Well, both my mechanic and I thought we had it - but when i got home the relay started to buzz again. Very frustrating. There is a black device on the left fender just behind the window washer reservoir with a cable going to it from the firewall and an electrical connection. When the relay buzzes I lift the handbrake and the buzzing either intensifys or stops and the device mentioned above vibrates. Very strange...
Could you take a picture of the device? If you can upload it to

and post the link so I can see it, this is a strange one indeed.
Customer: replied 5 years ago.
You're earning your stipend on this one. Car is still at mechanic. If he does not resolve the problem, I'll send that photo. I think it is the electronic speedometer and also might control cruise control, that must be the cable coming out of it and into the firewall at the driver's side. LOL, just not sure what lifting the handbrake has to do with that device... Just for you satisfaction I will keep you posted. ,
Thanks! I really enjoy oddball/challenging issues. Have a good night my friend.
Customer: replied 5 years ago.
,Hello, been a while. Black box is cruise control. Mechanic was certain there was a short in the ignition switch. So we replaced that - OMG, still have the buzzing but less often. Frustration level now VERY high...