505 'Non-Standard' electrics bite again

[baldrick56]

G'Day All,
having put some effort in recently to a bit of a 'Refresh' of the 505 it was a bit disappointing to have a near breakdown on Weds night. We'd done the airport run to Sydney earlier in the day to collect son & daughter-in-law in the "Limo." On the way back weird things started to happen with the electrics, first the wipers packed up (intermittent rain was happening ), coincident with this the battery warning light came on (nice & bright after my dash bulb replacements), then the indicators stopped working (I know I made the dash illumination BMW red but that's ridiculous ). At least the main lights were still going so we made it back with frequent stops to wipe the screen. First thought was alternator's packed up but there had to be something else too. I noticed that every time I braked (engaging the brake light circuit) the temperature gauge plunged to zero (fuel gauge also seemed affected), and the battery warning light got yet brighter. The dash clock also seemed to be desperate to join the party alternately being off and on.

With my limited expertise in electrics symptoms looked typical of an "earthing fault" to me so yesterday first tested the battery which reported "health 100%, charge 97%" - think alternator's OK. Then I took off the panel under the steering col, took off the stalk switches & tested with a multimeter (they were both operational). There was an 'earth' connection to the bracket under the wiper switch which was very obviously not an 'original' fitment. back up the line from this it was grafted three ways, one a very thin wire (looked like speaker cable), one thicker red wire, the third into the 'original' wiring harness (black cable). Other side of the bulkhead (near the fusebox) there's a 'multisocket' not connected to anything with the same bundle of colours as the harness under dash, indeed there's continuity between 'earth' terminal & black terminal on multisocket. In all the faffing we must of reconnected the battery a bit 'early' (bad practice ) 'cos when I was refitting the 'earth' I got a spark! With the multimeter there was 11.9 volts between the rogue 'earth' terminal and 'real' earth. Decided to replace everything except the mystery 'earth' after which wipers worked again, indicators ditto, battery warning not lit with engine running. Biggest surprise of the lot (given the thin wire / red wire disappeared behind the central console at about the 'latitude' of the radio) was the radio appeared to still work. Think I'm out of cunning plans now other than to drive around for a while to see what (if anything) doesn't work.

One other piece of 'trivia' when the 505's between gigs I'm fastidious about disconnecting battery - without doing so between a month & two its too flat to start the car. Now same applies to both the ZR & the Smart BUT these last two are shot full of computers, immobilisers, alarms, & God knows what other power-sapping shite so only a surprise in case of 505 which should only be powering dash clock 'at rest.'

Does anyone have any further insights??
Thanks, Rob

 

[Haakon]

Yuck... Have bought a few cars with wiring like that - I've always made the effort to strip out all the hacks and crappy work and put it all back to original. And re tape looms etc.

Those coloured crimp terminals are the work of the devil...

 

[COL]

I would trace out the additional wiring and see where it goes and what it was intended to do. If it is redundant I would remove it. If it is being used I would check the joints and where it is fed from as some people just grab a feed from where ever to power the added accessory.

If you are getting a flat battery with the car standing for some time, there could be two causes #1 there is a current draw from the battery which is discharging your battery over time or; #2 the battery is on its way out and can't hold a charge for that amount of time.

If you are getting a spark when you connect that earth wire and the ignition is turned off the I would say that you have found your discharging issue. As above trace out where the wire goes, you may need to move the feed of the accessory to after the ignition so that the battery does not go flat when the car is not in use.

I have a modern head unit in my R12 that obviously needs power to retain its memory. I can leave my R12 unused for several months and the is more than enough capacity left in the battery to crank up the oil pressure and fill the carburettor with fuel using the mechanical fuel pump and also start the car.

Can be a bit of a headache tracing wires in looms but its the only way to undo the dodgy work of a previous owner.

Nothing wrong with those insulated crimp connectors if they are crimped properly using the correct size lug and the correct crimping tool.

 

[Haakon]

Nothing wrong with those insulated crimp connectors if they are crimped properly using the correct size lug and the correct crimping tool.

I disagree, they're bloody awful. A proper open brass crimp done with the right tool and insulated with heat shrink is good, that how factory looms do wire joins.

But these cheap and nasty things are horrible...

 

[COL]

I disagree, they're bloody awful. A proper open brass crimp done with the right tool and insulated with heat shrink is good, that how factory looms do wire joins.

But these cheap and nasty things are horrible...

I use those style of crimps everyday among others, like all the types of crimps they are fine if you use the right size crimp for the wire and use the correct crimping tool. Willing to give a lesson to anyone that wants to know how to correctly crimp cables.

 

[Haakon]

They can be made to work, but they’re still poor quality and poor practice.

Do what the OEM loom manufacturers do - brass crimps with proper strain relief on connectors. Heat shrink to insulate and seal. NO SOLDERING!

 

[baldrick56]

Joy was short-lived, with the "false" earth terminal removed & taped up I thought I'd also attempt to trace where the red +the thin wire originate so yesterday removed the radio, checked it had been wired correctly (it needs a 'permanent' live plus a 'through key' live) - it was - the permanent live via fuse 14, & the other via fuse 5 (Haynes diagram not lying for those!). Couldn't see either of the mystery wires around the back of the radio. I'm thinking now they may have been for a carphone - there's two screwholes near the gearstick which had the cradle once possibly. Anyway even with these out the way the fault condition was triggered again very quickly. A clue is the brake light circuit which provoked temperature & fuel gauge needles to drop when activated so I guess I need to check that next. Apart from the battery warning light glowing the wipers, indicators, and windows don't work when fault is triggered but work again if you kill the engine & reswitch on ignition. I guess the other thing is to cut (all four strands) of the mystery wires & see if that cures anything?

 

[Haakon]

If activating one load causes other components to act up, go looking for what is common. Get out the wiring diagram and work out if there is a common earth (and then check it well secured etc) or if there is a common power supply (put a multimeter on the common point and see if there is a voltage drop when you press the brake). There will most likely just be a poor connection somewhere.

A 505 is about as simple as it gets really. With a wiring diagram, a multimeter and a methodical approach you'll sort it out no worries

 

[COL]

If activating one load causes other components to act up, go looking for what is common. Get out the wiring diagram and work out if there is a common earth (and then check it well secured etc) or if there is a common power supply (put a multimeter on the common point and see if there is a voltage drop when you press the brake). There will most likely just be a poor connection somewhere.

A 505 is about as simple as it gets really. With a wiring diagram, a multimeter and a methodical approach you'll sort it out no worries

Earths are not the only place where you can have issues with corrosion, although these are the easiest to check as there are only a handful of them in most cars.

Anywhere there is a connection there can be a problem, such as at wiring harness plugs and sockets, fuse boxes and switches etc.

Like Haakon says you will need a wiring diagram and a multimeter and a bit of time and patience.

The things to ask yourself are the items that are playing up on a common fuse etc

 

[baldrick56]

Anyone got any clues as to what the component marked '45' (in the red cloud) is? 45 in the "key" to diagrams is "Battery" & indeed there are two things marked '45' (gotta love Haynes ) Other confusing thing about the diagram - it suggests that the +ve goes right through the fusebox (OK not the two relays possibly) & "everything" the other side you'd expect to be live which is not the case as the keyswitch comes into play somehow - always find these line diagrams confusing
Regards,
Rob

 

[baldrick56]

Well possible progress of a sort, tested the voltage at the rear brakelight holders - around 10V each, so I've lost ca. 2.5V in the cabling / switchery but didn't think that too bad for 30+ years wear & tear. Then decided I'd have to remove the whole dash just to "get at" any meaningful wiring. In the event didn't get that far but did get the central panel removed - first thing noticed was a wire (brown) & plug just hanging there - it had next to zero resistance between it & earth so guess its intended as an earth but nothing obvious to plug into on the rear of the dash panel. Just for shits and giggles decided to unplug all the switches behind this section then start up again. So far its been running more than 10 mins & no repeat of the fault (did find indicators wouldn't work unless I reconnected hazard warning switch after which they did). Next stage will run around for 50kM or so with panel removed to see if fault reoccurs.

 

[baldrick56]

Sadly the wiring machinations didn't do much - got about 3kM into my 50kM "test run" before it went wrong again, same symptoms. The subplot to all this was that we'd bought tickets to the annual 'Abba Festival' at Trundle (first time back this year after Covid) and I wanted 'period-correct' transport there if possible (also having some issues with the MG with time pressing). To that end I booked it into the Auto-Electricians a few days before the festival to see if they could do better. Predictably on the day it behaved perfectly on the 6kM run to the workshop - left it with them having described the problem in detail. They ran it on and off through the day and it continued behaving perfectly . When I went to collect the guy said "Alternator, got to be the Alternator, we see dozens like this doing the same thing."

Now in 2020 I did have some issues with the Alternator and ended up fitting a new Regulator unit (Hella brand), car's done few kM since - maybe couple thousand at most. Alternator checks out OK (when problem's not present) using one of those cheap 'bunnings' traffic-lights checker devices. The thing which really strains my credibility is that the first night the problem arose I drove 100kM with the dash warning light glowing all the time, with headlights on, when I checked the state of the battery next morning it was 97% charged - how can that be squared with faulty Alternator?

 

[baldrick56]

Sadly the wiring machinations didn't do much - got about 3kM into my 50kM "test run" before it went wrong again, same symptoms. The subplot to all this was that we'd bought tickets to the annual 'Abba Festival' at Trundle (first time back this year after Covid) and I wanted 'period-correct' transport there if possible (also having some issues with the MG with time pressing). To that end I booked it into the Auto-Electricians a few days before the festival to see if they could do better. Predictably on the day it behaved perfectly on the 6kM run to the workshop - left it with them having described the problem in detail. They ran it on and off through the day and it continued behaving perfectly . When I went to collect the guy said "Alternator, got to be the Alternator, we see dozens like this doing the same thing."

Now in 2020 I did have some issues with the Alternator and ended up fitting a new Regulator unit (Hella brand), car's done few kM since - maybe couple thousand at most. Alternator checks out OK (when problem's not present) using one of those cheap 'bunnings' traffic-lights checker devices. The thing which really strains my credibility is that the first night the problem arose I drove 100kM with the dash warning light glowing all the time, with headlights on, when I checked the state of the battery next morning it was 97% charged - how can that be squared with faulty Alternator?

PS - As you may have heard the Trundle Abbafest got cancelled due to weather!