Need some help with relays
03-24-04, 02:26 AM
#1
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Need some help with relays
Okay, here's the situation..I have 2 relays wired into my wolf3d setup (standard bosch automotive relays).. one relay is for the ECU and the other is for the fuel pump.. I just got my car out of winter hibernation and was doing some tuning.. everything was fine until I turned the car off... turning the car back on, my fuelpump and ECU did not turn back on.. After pulling out the trusting multimeter, I found that the relay for the ECU was shorted (I ohmed out the coil pins and got continuity).. To verify, I replaced the ECU relay with the relay for the fuelpump.. Turn the switch on and got power to the ECU.. however, once I turned the key off, and turned it back on, I once again had no power to the ECU.. I had blown another relay!
Could this be a conicidence? could both relays been on the verge of dying and decided to croak at the same time? I am kind of hesitant to go out and purchase a couple more relays only to have them either blow again right away (or if I'm miles from home).. What could be causing the relays to go bad? I am energizing the coil using a line tapped into a ignition switched power source..
I pulled one of the relays apart and could not find any evidence of arcing or burned contacts.. I also gave the relay a few raps with a screw driver and the reading between the coil went from continuity to 80 ohms...
Any suggestions on what to look for? or shoudl I just risk getting a new set of relays and keeping my fingers crossed that these old relays were just bad?
Could this be a conicidence? could both relays been on the verge of dying and decided to croak at the same time? I am kind of hesitant to go out and purchase a couple more relays only to have them either blow again right away (or if I'm miles from home).. What could be causing the relays to go bad? I am energizing the coil using a line tapped into a ignition switched power source..
I pulled one of the relays apart and could not find any evidence of arcing or burned contacts.. I also gave the relay a few raps with a screw driver and the reading between the coil went from continuity to 80 ohms...
Any suggestions on what to look for? or shoudl I just risk getting a new set of relays and keeping my fingers crossed that these old relays were just bad?
03-26-04, 06:22 PM
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OK, a relays coil will read continuity to 80 due to the coil resistance.
Try using the battery power and a ground to activate the relay. If it works, you have other problems.
I will also need other points of wire contact you made for ECU power and for fuel pump.
Try using the battery power and a ground to activate the relay. If it works, you have other problems.
I will also need other points of wire contact you made for ECU power and for fuel pump.
03-26-04, 11:20 PM
#3
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Yeah, I would check to see if the relays work outside of the vehicle.
Check with the DMM if your get resistance across the low-power side, then connect +12VDC and ground to check if you get the high-power side to switch.
Relays will rarely fail unless they are submerged in water or run too much current through the high side.
-Ted
Check with the DMM if your get resistance across the low-power side, then connect +12VDC and ground to check if you get the high-power side to switch.
Relays will rarely fail unless they are submerged in water or run too much current through the high side.
-Ted
03-26-04, 11:31 PM
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86 is the relay switching (control) circuit input.
85 is the relay switching (control) circuit output (ground)
30 is the power circuit input.
87 is the power circuit output.
Relays follow an industry standard, so by following RETed's advice, you would check continuity between 86 and 85. If it checks good, apply power to 86 and ground 85. This will close the contactor between 30 and 87. Now check for continuity between 30 and 87.
85 is the relay switching (control) circuit output (ground)
30 is the power circuit input.
87 is the power circuit output.
Relays follow an industry standard, so by following RETed's advice, you would check continuity between 86 and 85. If it checks good, apply power to 86 and ground 85. This will close the contactor between 30 and 87. Now check for continuity between 30 and 87.
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