The first AUX relay failure ever?

[AugustneverEnds]

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

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.

[AugustneverEnds]

And while I'm out here in the cold I figured I'd measure the resistance of the coil: .6

That's a bit low isn't it?

[AugustneverEnds]

Ahh schematics are a wonderful thing and so are 37 year old Bosch AUX relays; of course the white wire I found connected to the mystery relay belongs on AUX I and now that it's back where it belongs everything is working again with the old relay. :cheers:

Still not starting but maybe the coil is the reason for that.

[David T]

Verify the presence of spark or give it a quick shot of Ether. Do you hear the fuel pump priming? Does the CSV spray fuel? Are the ballast resistor connections rusty? Did you push on the air sensor plate to see if there is any resistance? The stock ignition coil is not a high failure part even after all these years. Is it a stock ignition coil?

[AugustneverEnds]

Verify the presence of spark or give it a quick shot of Ether. Do you hear the fuel pump priming? Does the CSV spray fuel? Are the ballast resistor connections rusty? Did you push on the air sensor plate to see if there is any resistance? The stock ignition coil is not a high failure part even after all these years. Is it a stock ignition coil?

I tried starting fluid and no start.

Fuel pump is working. I jumped the RPM relay just to see if it made any difference, it did not.

CSV has been out of a commission for a few years now because the blades on the thermotime switch broke off. I have a new TTS in hand, need to get an adapter from Deloreango to fit it.

I snipped off the old terminals and replaced with new ones on the ballast resistor, no start still.

Checked the connection between the distributor and the ignition ECU, looked fine.

After cranking attempts the air sensor plate does have resistance. Coupled with everything else I have tried I'm leaning towards an ignition problem. I have a helper coming by tomorrow so he can turn the key and I can look for spark on the plugs. I replaced the ignition coil in 2017 with a NOS Bosch one from DMCMW. My old one was full of corrosion and debris and causing stalling and erratic idle. I measured .6 ohms last night on the coil. I think I remember reading somewhere it's supposed to be .9-1.2 ohms so that's why I suspect it.

[Bitsyncmaster]

My car needs the CSV to start if the car sits for a week or more without running. My hot start relay can run the CSV without the thermotime switch if you want to go with that fix.

[AugustneverEnds]

My car needs the CSV to start if the car sits for a week or more without running. My hot start relay can run the CSV without the thermotime switch if you want to go with that fix.

For the past three years or so I have been giving it a shot of starting fluid if it has been sitting for a while. In the summer I drive it almost everyday and it starts up easily so that's why I have been putting off replacing the thermotime switch. I bought Deloreango's aftermarket version last November and overlooked it's longer and a smaller diameter compared with the original and needs the screw adapter they sell. I plan to order that with a few other items I've had my eye on.

I do have my eyes on your solid state relays, the fan fail, and electronic otterstat. Some previous owner totally removed the fan fail relay receptacle and hardwired the wires together. Since it's such a mess right now anyways I figure now is a good time to finally finish undoing all of the PO's hacks. Hopefully this year I can get the A/C working and it would be easier on my mind knowing the fans are not activating at the same time and putting the old wiring under that much load.

Of course first I need to get it running

[Ron]

For the past three years or so I have been giving it a shot of starting fluid if it has been sitting for a while.
...
Some previous owner totally removed the fan fail relay receptacle and hardwired the wires together.

Ugg! -- I've seen that a few times.

Just in case-
If you haven't removed the hardwire job because you wanted to see what the PO was up to (or ??), definitely do so before installing the new TTS -- If the rest of the circuit is stock, the PO created a dead short through the TTS's bimetal arm to ground (when it's cold), and one through one of the arm's heating coils (when it's hot). The entire circuit is unfused (W/R wire) and the CSV would not work.

[AugustneverEnds]

Ugg! -- I've seen that a few times. :confused2:

Just in case-
If you haven't removed the hardwire job because you wanted to see what the PO was up to (or ??), definitely do so before installing the new TTS -- If the rest of the circuit is stock, the PO created a dead short through the TTS's bimetal arm to ground (when it's cold), and one through one of the arm's heating coils (when it's hot). The entire circuit is unfused (W/R wire) and the CSV would not work.

I had no idea screwing with the fan fail relay could short the TTS. That makes sense to me because when I bought 10287 the PO mentioned he needed starting fluid to get it going if it hadn't been running for a while and at that time the TTS was intact and plugged in but obviously not firing the CSV. Back then I was too inexperienced and timid to try to repair it. I know the CSV is good as I have done the plug swap before.

Been digging through my crate of spares searching for an extra relay receptacle. The ironic bit is someone hardwired the fan fail and kept the blue fan fail module :confused2:

[Ron]

I had no idea screwing with the fan fail relay could short the TTS.
Been digging through my crate of spares searching for an extra relay receptacle. The ironic bit is someone hardwired the fan fail and kept the blue fan fail module :confused2::banghead: Nix that idea -- I was up way too late and somehow thought you meant the warm up relay...

Going back to bed.

[AugustneverEnds]

:banghead: Nix that idea -- I was up way too late and somehow thought you meant the warm up relay...

Going back to bed.

Happens to me all the time. I think I'm driving myself insane working on the car at night when my brain is screaming to stop. Last night I was so pissed when the instrument cluster lights weren't coming on I detached the binnacle to check the plugs when reality slapped me silly and I remembered the rheostat has to be connected for the cluster to light up :facepalm:

That ended the night for me

[AugustneverEnds]

Well 10287 is awake, seems like the ballast resistor was the cause of the trouble.