The first AUX relay failure ever?

[AugustneverEnds]

Hey everybody, hope everyone weathered the winter and is out with their cars enjoying the spring

I've had a very eventful past few days. I needed to replace the terminal for fuse 16 (reverse lights) as the light green/white wire partially melted last summer. To be frank my relay compartment is definitely not the tidiest in DMC land though I thought my days of previous owner created messes were behind me (in 2016 I removed the after market radio, extra antenna, amplifier, DVD player, backup camera and alarm [the worst mess of all]) So I was very surprised to find a black Matsushita relay/module lurking next to the AUX/main relay. It was connected to a black wire, orange wire and a red wire that was spliced to a white wire that was part of the main bundle that is taped together on the driver's side of the center console that goes somewhere under the dash. The black and orange wires didn't seem to be connected to anything. After I removed this stowaway I lost power to everything on fuses 1, 2, 3, 4, 5 and 7.

Completely stunned I put the white wire back onto the mystery relay but that didn't fix anything. Since I had power to all of the stuff powered through the second AUX relay, I put its brown wire onto the first AUX relay and still nothing. As a last resort I jumped the AUX I relay's brown wire direct to its white wire and presto! dash warning lights back on, frequency valve buzzing etc.

I have never heard of anyone else having a bad AUX relay but there has to be a first for everything right? I'm hoping this is all it is and finding that extra relay is just a coincidence.

[DMCMW Dave]

I have never heard of anyone else having a bad AUX relay but there has to be a first for everything right? I'm hoping this is all it is and finding that extra relay is just a coincidence.

I've never seen one fail. It's possible that all the excess aftermarket stuff you removed had overloaded it. The OEM relay is a very beefy part.

[Bitsyncmaster]

I've never seen one fail. It's possible that all the excess aftermarket stuff you removed had overloaded it. The OEM relay is a very beefy part.

I did some testing a long time ago and the current in each was way under the 70 amp rating. I use my solid state relays for both but mine don't have the larger load pins like the OEM parts.

Did you test that the coil is getting 12 volts and ground?

[AugustneverEnds]

I did some testing a long time ago and the current in each was way under the 70 amp rating. I use my solid state relays for both but mine don't have the larger load pins like the OEM parts.

Did you test that the coil is getting 12 volts and ground?

Pardon my blockheadedness, electrical is not my forté, do you mean the ignition coil? If that is what you mean then no I haven't. Can do today

[Bitsyncmaster]

Pardon my blockheadedness, electrical is not my forté, do you mean the ignition coil? If that is what you mean then no I haven't. Can do today

Mechanical relays have a coil of wire that creates an electromagnet that pulls the contacts open or closed. If the control voltage (power to the coil) was not there then the relay would not have been the fault.

[David T]

It is possible that aftermarket additions or PO modifications contributed to the AUX relay's early demise. Not a typical failure prone item.

[AugustneverEnds]

Mechanical relays have a coil of wire that creates an electromagnet that pulls the contacts open or closed. If the control voltage (power to the coil) was not there then the relay would not have been the fault.

That makes sense. Before this episode began the car didn't start when I tried it for the first time since last fall. It seems like an ignition issue because I pulled spark plug #3 and saw nothing when my helper cranked it. The coil was replaced in 2017 with a NOS piece so it's not out of the question. I need to test the coil for resistance and voltage. Should have today but I wimped out since it's 37F out and snowing. Got spoiled yesterday when it hit 67F

David T
It is possible that aftermarket additions or PO modifications contributed to the AUX relay's early demise. Not a typical failure prone item.

Well if 37 years of service and abuse is an early demise that's not too shabby. I'll check the coil tomorrow and if I need a new one I will order the relay too

[81dmc]

That makes sense. Before this episode began the car didn't start when I tried it for the first time since last fall. It seems like an ignition issue because I pulled spark plug #3 and saw nothing when my helper cranked it. The coil was replaced in 2017 with a NOS piece so it's not out of the question. I need to test the coil for resistance and voltage. Should have today but I wimped out since it's 37F out and snowing. Got spoiled yesterday when it hit 67F



Well if 37 years of service and abuse is an early demise that's not too shabby. I'll check the coil tomorrow and if I need a new one I will order the relay too

Uhh, they are not talking about the ignition coil, but rather the coil INSIDE the relay...

Like Dave said, check power to the two pins that power the relay. Normally, power and ground on 85 and 86 on relays will activate them. So turn the ignition switch on and check for voltage between those two pins.

[AugustneverEnds]

Uhh, they are not talking about the ignition coil, but rather the coil INSIDE the relay...

Like Dave said, check power to the two pins that power the relay. Normally, power and ground on 85 and 86 on relays will activate them. So turn the ignition switch on and check for voltage between those two pins.

See what I mean about blockheadedness? Thanks for the clarification and which wires belong on which pins. I was forlornly hoping all of my issues might be solved in one shot. Getting ahead of myself

[AugustneverEnds]

So 12V going into pin 85 and almost nothing coming out of the opposite side. The relay felt like it clicked in my hand. Unless the ground is bad this relay seems dead.