Electrical Advice Needed

JimNB · 05-10-2002, 04:10 PM

Today my car died. Cranked and cranked and cranked, but would not fire.

Trouble light shows power to the top fuse (rear block of 3), through fuse to post, from post to a relay. Which is where I am stuck.

The relay is (I think) the "Auxiliary Starter Relay". There are 3 wires coming out of the rubber base of the relay. At least one of them should show power but none do.

Has my relay gone bad ? How can I be sure.

Thanks.

Jim

PS> If I do need one, where the heck can I source one. It is a Wehrle Part # 901.615.109.03

1bar · 05-10-2002, 06:45 PM

You can get these relays here from Pelican, at other mail order spots, or at a local dealer. They cost something like $20-30 US. There are two types, classically called the "Red Relay" and the "Black Relay". You want to keep them separate, and you probably should have a spare of each in your emergency kit.

If you suspect a relay, the best thing to do is swap in a "known good" relay. If you don't have a new one, pull the relay for the horn or the windshield washer pump and swap it in the suspect location. If it's the relay, you should start right up.

Sometimes it's the relay base, not the relay itself. These things have brass spring contacts that can become loose or can corrode due to weather and just plain getting old. Try a scrap of emery cloth on the relay feet (the pins coming out the bottom) and gently scrape the inside of the contact in the socket to clean it up a bit, then re-insert the relay.

It's odd, but I've had my car just not work one day - pull the fuel pump relay out, clean the leads, and stick it back in - voila! Back on the road. I've also had the same experience where the relay itself was just bad. Worked when I parked it, didn't work a week later when I tried to start the car. Put in a new relay and off and running.

Good luck!

JimNB · 05-11-2002, 04:30 AM

I took a shot at cleaning everything up and re-assembled. The car started no problem.

I am still a little leary that I have not solved the problem but have a couple of questions that hopefully someone can help with:

On the three fuse block in the engine, should there be power to the top fuse with the ignition off. In other words is this what is referred to as a hot lead.

Also, could the fact that I just had a rust proofing done have anything to do with my problem.

Thanks in advance.

1bar · 05-12-2002, 01:42 PM

Hey, Jim. Congratulations on getting back on the road. No, you haven't solved the real problem - unfortunately there IS no cure for old age! I guarantee you'll do this again before long.

On my '77 the top fuse on the 3-fuse panel in the engine compartment is definitely at +Battery (+12V) when the ignition is off.

As to the rust proofing, it's certainly possible that the volatile solvents in the undercoat deposited a thin film of material a few places as it was evaporating. It's also possible that it was simply coincidence. If cleaning the base of the relay fixed the problem, then recall what you saw on the relay pins. Was there green corrosion or what looked like an organic deposit? That's the only clue you're likely to get.

JimNB · 05-13-2002, 02:08 AM

Yes there were green deposits but last night, I also found a bad ground in the 14 pin connector.

To make a long story short, the wiring sparked and smoked.

I disconnected the battery, and disassembled the "chassis" for the wiring.

The underside is a mess. The wiring is all frayed and decayed.

This is going to be a challenge. Any procedures out there for testing wiring.

I am assuming I have to go wire by wire until I find the cause.

304065 · 05-13-2002, 05:47 AM

Jim,

You are not alone. My 1971 E (T Shell) had a similarly toasted wiring harness that was just waiting to fail/ignite. It's not hard to fix in a way that will be good for another 32 years.

If I understand you correctly, you removed the "console" from the port side of the engine compartment and everything had been cooked. There's a 14-pin connector going into the harness, and the 14-pin connector going OUT.

The easy way out is to buy another one on EBAY- I have tried to buy 2 of them for about $50 in the last six months, and they seem to go for a little more than that, complete with voltage regulator and everything else. But that's no guarantee that it will be any better than what you have, unless the seller can prove it.

I would download the factory wiring diagram from the Pelican main page, and get yourself a multimeter. Doesn't have to be expensive for what you're going to use it for (but if you want to buy a $300 Fluke meter I say go for it !).

First step is to identify those wires that are obviously fried: melted insulation, often melted to another wire, or insulation that looks bumpy, like the wire got really hot-- these are the first pieces to replace.

The sockets were available from Stoddard's last time I checked. They are NOT cheap and the pins (on the female side) are about a buck a piece. But because the console was used all the way up to the 964 the parts should be available if yours are cooked.

Now, using the wiring diagram, you want to check for continuity in the wires- the leftmost 14-pin connector on the diagram is the one you should focus on. Ignore the fact that it's only shown as a single row of pins and the connector is actually 2 rows of 7- pin #1 is on the left side of the diagram, and on the connector is marked with a 1. Put the volt-ohm meter on the ohm scale, and check the connections on the 14-pin connector against the sockets on the console. If there's supposed to be a connection and it's good, you should get zero ohms, or something close to it. If you get "infinite" ohms that tells you that the circuit has failed.

Patience and the wiring diagram are your best allies here, good luck. If you need to replace any of the wires be sure to do so using the exact same color as the factory, you will be happy (as will future generations) you did so when it comes time to diagnose electrical faults.