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  #41 (permalink)  
Old 12-07-2018, 01:17 PM
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What initially comes to mind is that the only thing those three have in common is the light switch itself....
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Old 12-07-2018, 02:14 PM
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So, with that in mind, here's the situation as I understand it. With fuses 7 and 8 out of the car, and the light switch off, if you start the car and turn the light switch on, everything dies.

If I have that right, then I would remove the light switch from the dash and remove the three wires off it. They are BROWN, RED, and GRAY. Brown is the hot wire. Start the car up and touch the brown wire to the gray wire and tell me if the parking lights come on or if the car dies.
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  #43 (permalink)  
Old 12-07-2018, 04:39 PM
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Bad grounds can cause some strange problems. ERAs typically have an engine ground strap, a ground strap on the trans and a cable from the battery to the frame.

I would clean them. You can measure resistance across them with a DVM when the problem is happening.

My theory is the headlights have a very high draw. I wonder if there is 12v at the head lights, but not enough amps to light them? That is easy to check.

I actually enjoy chasing electrical problems. It is a sickness.

John
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  #44 (permalink)  
Old 12-08-2018, 03:39 PM
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Quote:
here's the situation as I understand it. With fuses 7 and 8 out of the car, and the light switch off, if you start the car and turn the light switch on, everything dies.
Correct.

Quote:
If I have that right, then I would remove the light switch from the dash and remove the three wires off it. They are BROWN, RED, and GRAY. Brown is the hot wire. Start the car up and touch the brown wire to the gray wire and tell me if the parking lights come on or if the car dies.
Still dies.

I am occasionally able to have them light up, although if I just let it sit in that state, things die again in usually less than a minute.

(Note: I haven't actually been starting the engine for most of this, but instead have left the MSD kill switch on and just testing to see if the starter cranks. And now that I recognize it, I can usually just listen for the accusump to cut out when things go dead.)

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Bad grounds can cause some strange problems. ERAs typically have an engine ground strap, a ground strap on the trans and a cable from the battery to the frame.
Thanks. I only tested the resistance from the nut on the firewall to the engine block near where the ground wire attaches, but read zero in all cases.
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  #45 (permalink)  
Old 12-08-2018, 03:48 PM
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Just for yucks, bypass the main circuit breaker (mounted next to the starter solenoid) by connecting both wires that are on separate terminals to the same terminal.
Note, I haven't tried this yet, but am increasingly suspecting this is where the problem lies. The reason I hadn't tried it was because if it isn't the problem, I was unsure what damage that might do elsewhere in the system. I forgot to mention this earlier, so Patrick I hope you haven't been assuming I already ruled this out.
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Old 12-08-2018, 03:59 PM
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Now repeat the test, but instead of using the brown wire, run a wire directly from the hot side of the starter solenoid and touch it to the gray wire. Tell me if it still dies or if the lights come on.
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Old 12-08-2018, 04:44 PM
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Alright, now we're getting somewhere. Connecting straight to the solenoid pos worked fine, so I figured the next step was to connect to the brown terminal of the ignition. When I did this I happened to hear a very faint clicking or intermittent buzzing. After turning out all the lights and repeating, I discovered some sparking inside of the clear connector for wire bundles labeled D (to I think C). I'm out of time for debugging today, but will take that apart (maybe tomorrow) to figure out what's going on there.

Thanks for all the help! Definitely feel like I've leveled up my electrical troubleshooting skills through this.
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Old 12-08-2018, 04:47 PM
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We're making progress.
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  #49 (permalink)  
Old 12-08-2018, 05:55 PM
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The brown wire should be a straight shot from were you clipped it to the ignition switch. Another brown wire then goes from that same terminal on the ignition switch to the left side screw of fuse #1. Both brown wires should always be hot. The wiring diagram I have does not tell me where that C to D plug is. But, if you heard sound, and saw light, from the wiring plug, then there will almost certainly be melting/charring or some other evidence. That buzzing/sparking can be caused by two different issues: 1) A fault to ground, such as frayed wires rubbing up against the frame of the car; or 2) Too much current going though too poor of a connection. There is no "fault" here, but you can still literally melt a wire's insulation. Take a photo of what you find and I bet Bob will recognize exactly what the plug is. He has a phenomenal memory, you know.
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Old 12-08-2018, 07:15 PM
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Here's a photo I took earlier after identifying the spark location. The arrow is just pointing to the connector, not to the specific spot - I couldn't tell precisely where since I had to turn the lights off to see the spark.
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  #51 (permalink)  
Old 12-09-2018, 08:20 AM
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OK, I think that plug is the (C) 12 PIN MULTI-CONNECTOR TO FRONT HARNESS (D) -- but I'm not 100% sure of that.
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Old 12-10-2018, 03:21 AM
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In the past, I have had this plug on my ERA become the source of an electrical fault. One of the wires going into the plug had a bad connection in the plug's block. This essentially caused a similar problem that Moriarty is experiencing. If it is the same plug, it is located (as memory serves) kind of in front of the passenger's seat up behind the dash. It is a rather large plug in my ERA (#375) and appears to link most of the dash to the primary electrical harness.
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Old 12-10-2018, 09:54 AM
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Somewhere between your two cars, and my car, the wiring harness got changed for the connectors to the front harness. Apparently Bob upgraded the one connector that you guys have to a split "high amp" version. See the rip below from my wiring harness that you two do not have. If that's the connecting plug that has failed (Your "C" to "D") then an upgrade to the connection would not be difficult.

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Old 12-10-2018, 10:35 AM
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When I assembled my car, not everything electrical worked initially. I discovered that within these wire harness plugs, not all the retaining tangs were set, meaning that the wire would be pushed backwards out of the connector when assembled. I found three wires that "clicked" into place when I pushed the wires in. It's possible that, in Moriarty's case, the connection worked initially but vibration and time has caused it to break connection, which could make the spark that was seen.

Regardless, I think it would be good advice for anyone building a car to take a couple minutes and push the wires into the connectors before assembly - easiest thing to do and it could avoid a lot of problems.

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Old 12-10-2018, 11:28 AM
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Kevin:
Now that you mention it, that is exactly what the problem was with my ERA. One of the wires in that connecting block was kind of backed out and by pushing each in, one by one, I did hear a kind of faint click which solved the problem. I recall being on the phone with Bob a few times as he walked me thru the diagnosis and process.

Patrickt:
It is very nice to know that as time has moved on (some 26 years since my ERA build) that small and constant significant refinement has been made by ERA (Bob P). When I am up at the ERA Xmas party (this coming Friday) I will make sure to meet with Bob P (if he comes down from the upper nether regions of ERAs factory). 8-)
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Old 12-10-2018, 12:40 PM
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It's hard to tell by just gazing up under the dash, but the high amp connector looks like an Anderson Power Products plug. Bob would know for sure.

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  #57 (permalink)  
Old 12-10-2018, 06:50 PM
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Nice. Yeah, here's what my connector looks like currently.



Should I ping Bob to see if he has any instructions for making this upgrade?

Last edited by Moriarty; 12-10-2018 at 06:59 PM.. Reason: fix image attachment
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  #58 (permalink)  
Old 12-10-2018, 06:58 PM
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I would. I think the four wires that will require two hi-amp connections are the BROWN, WHITE, BLUE, and WHITE wires (yes, two different white wires). And that connector fitting for the brown wire looks pretty bad. Or maybe just use hi-amp connectors on all of the fatter wires and regular connectors on the rest.

Last edited by patrickt; 12-10-2018 at 07:10 PM.. Reason: Pic comes up now....
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  #59 (permalink)  
Old 12-11-2018, 03:04 AM
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Quote:
Originally Posted by Moriarty View Post
Nice. Yeah, here's what my connector looks like currently.



Should I ping Bob to see if he has any instructions for making this upgrade?
No harm in doing that. I would like to know what he suggests.
The plugs are in such an awkward location which presents a challenge all unto itself.
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Old 12-11-2018, 03:55 AM
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Those connector terminals are not up to task, as seen in the discoloration of the connector plastic and the start of plastic melting.
So some redesign with some relays in the high current paths may help.
The signal paths to activate relays can remain as desired.

Examples would be a headlight relay is never fitted at the back of car.

Fuel pump relay would be between battery positive and the pumps, keeping the high current paths as short as possible.

Gary
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