Wedge Electrical issues [TR8]

[JodyFKerr]

Hey guys,

Please someone poke holes in my il-logic where appropriate.

Bought car: alternator and battery work.
Drive car: alternator dies.
Replace alternator: new alternator dies(?) (haven't determined for certain yet, have to finish charging the battery.

I checked all my continuity from the alternator back to the battery. It's a clean circuit. Earlier today the battery was putting out 12 v. Reading at alternator was 11.43. This is after discovering that the negative battery cable was super hot.

My working premise is that the alternator(s) were overworking themselves to death trying to get a charge into the battery which could end up accepting it because of the resistivity of the negative battery cable connection.

As I'm still fairly ignorant of the peculiarities of the TR8, is there anything else I should be looking into? What I don't want to do is simply go buy another alternator without understanding why it happened.

 

[tr8todd]

How's the engine ground? I usually add one. Good spots are under a transmission bolt and or under the distributor hold down bolt. The battery ground is thru a bolt and a couple of nuts that tighten onto the sheet metal in the trunk. Crappy design. I like to take a bolt and weld it to the trunk floor pointing up and then bolt the ground to that. Another common poor grounding spot is the rear tail lights. Doubtful that spot has anything to do with your issue, but those poor grounding tail lights cause some pretty frustrating dash problems. Things like all the lights go out when you turn on the wipers. Fix for that is to make up a pigtail that has a female terminal on one end and circle on the other. Insert the female onto the male spade on the back of the tail light housing and then put the circle under one of the lights retaining nuts. Seems the factory realized this could be a problem, so they went ahead and installed the grounding spade on the back of the housing, but never actually put the ground wires on.

 

[JodyFKerr]

Engine has a proper ground wire already installed on that side. While I was at it I disconnected it and cleaned the connections.

I'm used to wacky electrics, but this scenario isn't one I've seen before.

Jody

 

[GBRandy]

Very fuzzy in my brain is a cloud about an issue with the long battery cable from the battery to the alternator corroding in some cars. It drove the resistance very high and caused all kinds of issues.

I have never had the issue and have no idea how to check for it.

Anyone else remember that?

 

[JodyFKerr]

So I think I got it. Basic engineering issue of great big bloody long wire from front to back paired with corroded body contact on the negative cable coming from the battery.

Cleaned every stinking connection from nose to tail, now I've got ~14volts at the alternator and ~13.5 volts at the battery running with the lights on.

But, just because it was a simple solution didn't mean it was easy.

Jody

p.s. The laughable irony in this is that I didn't follow my own instructions on buying a new car. Clean all the connections day one.

 

[JodyFKerr]

I decided to take the car for a test drive. Ran it for 15 miles. After driving I got the following readings.

Voltage at battery: 12.05
Voltage at alternator: 11.02

Not good. I'll fire it up in the morning and see if it reads correctly when cold. If it's still low on a cold motor, I think it points to the alternator. If it's a good reading, then it sounds like I've got hot wires, and I'll likely need to start looking at replacing some of the engine harness.

 

[Deleted member 8987]

The only real way to test battery cables is to load test them.
You can do it with the starter, in neutral, e-brake on.

Anyway, put a voltmeter lead at one end of the cable, the other lead at the other end.
Crank it.
Observe the voltage drop.

Now, if the car starts, cable is at least good enough for that, but, the output of the alternator should be connected directly to battery positive, and the voltages should be the same.
Unless the wire is routed through an ammeter.
If an inductive ammeter, no connections, maybe corroded wire, if a in-line ammeter, look for bad connections where it bolts on.

I cannot recall ammeter or not on a TR8.

While running and charging, you can also use a voltmeter to check for poor connections.
Current through resistance shows voltage.

 

[philman]

somebody somewhere had a problem with the positive battery cable chaffing where it is routed over the rear wheel arch. Maybe Ted at TSI? Another spot may be where the cable comes through the firewall underneath the carpeting on the passenger side.

 

[JodyFKerr]

So I think I may have found my problem.

and

This was all hidden under carbonized electrical tape that had been hidden under harness wrap. You know, 99% of the time I have electrical problems it's because of someone else's previous bodging.

Cut/spliced all the bad bits and replaced the alternator-starter wire. Tomorrow I'll test everything out to see if all the components are still good or damaged.

 

[tdskip]

I bet that does it!

 

[Mickey Richaud]

You know, as complicated as the Wedges seem, it's amazing how often the electrical problems are such simple fixes. And it's always the last place we (well, I, anyway) look! :wink:

 

[PATR8]

I would have agreed with you on that until my year long seach for the Lucas Lights gremlin. I have given too much of my life that I will never get back to trying to get my lift motors to work again. I feel as if Mr Lucas, from the grave laughs, at me everytime I fail to find the fault.

I have even gone so far as to try to start the conspiracy that Mr Lucas wants to return from the dead and to do so he must have a way to drain life from the living. He does this through his wiring and lights. Each time we must stop to fix something, something we have usually fixed before, he gains the life we have wasted fixing it. That is my story and I am sticking to it.

 

[JodyFKerr]

Oh, I had a 944 with wacky headlight issues. I tried everything, and then finally figured out that the connector where the relay attached was worn. The relay would vibrate loose enough to not function, not enough to fall out.

A little "engineering" fixed the problem.

Now if only my great emissions quest was as simply resolved.

 

[DNK]

What is the piece in front of the washer bottle?

 

[JodyFKerr]

What is the piece in front of the washer bottle?

I could tell you, but I'd have to kill you afterwards.


Actually, it's a fuel pressure regulator (presently set to 5 psi). The PO put that in. I think he bought the wrong fuel pump at some point, and that was his solution. It's presently working fine so I'm not inclined to try and remove it right now.

 

[DNK]

Works for me.

 

[sabot]

Is there a place to get a new harness for the 8's? Or is it best to make one, and from what sources?
Tom

 

[JodyFKerr]

These guys have great wiring harnesses.
https://www.britishwiring.com/Tri_TR.PDF

JOdy

 

[71MKIV]

That problem should have been obvious from the puddle of electrons on the floor. although come to think of it, it would only have been leaking when you were underway with the electrons scattered along the road.

at least you could get to it without having to be upside down and backwards or the thing shorted to the carbody :eeek:

 

[JodyFKerr]

Yeah. My biggest worry was that I would have to tear the interior apart.