Amazon: '66 Amazon Headlight > brake-light : gremlins

[BLS07]

Hello fellow Volvo enthusiasts !

Would greatly appreciate the imparting of some advice in respect of the following conundrum, please.

Vehicle spec:
Amazon '66 122, LHD, B20, and some months back I replaced dynamo with a nice alternator upgrade. All has been brilliant since that swap.

until..

Headlights had been fine, until an issue with original foot switch arose, currently working on getting that out of the car. Screws have ceased, and easing them out is taking a while.

I have an interim replacement in the car using a foot-dipper switch from Brookhouse Volvo. Which itself seems to be A-OK.

Standard wiring throughout the car, per Haynes and original Volvo manual resources to hand.

At foot-dipper switch, wiring is:
i) Two red, one larger gauge than the other. (main / high beam)
ii) One Grey (dipped / regular beam)
iii) One Yellow (power from switch)

Problem / Issue

1) Headlights are only both on when foot-dipper is set to main-beam ("high beam").

** Only front left headlight (and all til lights) on when foot-dipper switch is set to "dipped beam"

2) Brake-lights only "pulse" / "flash" when brake pedal engaged IF headlight switch on the instrument panel is OFF. (all the way in)

3) Tail lights all ON and A-OK when headlight switch on the instrument panel is ON. (just brakes don't "flash" per 2 above)

4) Indicators - all four work fine, all the time.

5) Front left parking light - "glows" when brake pedal is engaged. AND when regular-beam (dipped beam) is operating per 1 above.

Is this likely;

A) Something in engine bay section of wiring (connector / junction box or relays)

B) Something in the Grey wire from foot-dipper switch to the junction box

C) something else entirely?

Appreciate wiring / electrical fault tracing is oft more complex than this - but just wondering if there is an obvious answer that as a newbie to all this am not picking up on.

Would really appreciate your advice !

Cheers, BLS.

[Ron Kwas]

BLS;

Compliments in presenting the Pre and Post failure state and conditions...!

If all was working fine after Alt conversion, we can pretty much discount that, and Chg Sys wiring changes which were made at the time, and those would typically not be involved with the lighting anyway...

I recommend multiple applications of light oil or penetrating oils to help with extracting Foot Switch securing hardware...before removal, you might try removing just the wires and connecting them to replacement Foot Sw, then checking if fault remains...I expect it may be still present, and typically when circuits which are not tied together, all of a sudden become somehow related or inadvertently connected, it points to a compromised or even fully open chassis connection (what happens is, the wires of the two circuits stay together, expecting to be at zero/chassis potential, but they are not, tying the two circuits together)...odd symptoms and often very strange interactions result!...sound familiar?

Suggested reading:https://www.sw-em.com/electical_circ...it_Interaction ...then equip yourself with some ACZP (See: https://www.sw-em.com/anti_corrosive_paste.htm ) ... and clean and refurbish the chassis connections on the front of the vehicle, and I clearly recommend starting with those having to do with Lighting...also, clean and treat with ACZP, the individual connectors of the Lighting Hex Conn in the engine compartment!

I've highlighted the connections of interest in Red here: https://www.sw-em.com/Lighting_chass...s_hex_conn.jpg ...it's up to you to locate them...I believe you'll find them behind the Headlight Buckets, or just follow the Lighting harnesses there...

Please report back with results!

Good Hunting!

[BLS07]

Hi Ron,

Brilliant! Thank you for the detailed reply, advice and links.
Much appreciated.

I shall get stuck in to resolving this wiring conundrum and feedback.

Have a great weekend.

Cheers, BLS

[BLS07]

Hi Ron,

Thanks again for the suggestions and advice.

So far up I have done the following;

1) checked every external bulb and fitting front & rear
- in what felt like a possible (all too obvious) eureka moment, found the left front Parker light was truly done. Smokey glass. Blown.

- all other bulbs and fittings : fine and solid.

2) Checked fuse box: all good, the connectors are spiffing new anyway. Fuses all fine.

3) Checked the junction / connector box from left of engine re main light harness. Looked in very good knick, spades in pretty good shape largely clean.
- didn’t have time to “polish” them up today. No signs of corrosion or deathly sparky dust either.

4) Two earthing points, within front end of engine bay and both on chassis.
- left side just below the harness junction box in engine bay.
- right side same position, just opposing side of engine bay.
- image of both points attached here
- drilled & then screw through inside wheel hub / outer engine bay wall.

5) Interim Brookhouse Volvo issued dipper switch (recently installed this summer) ; removed grey wire (dipped beam / regular beam) as high beam works yet only left headlight ON when diaper switched to “dipped beam”
- just out of curiosity & elimination ;

All without change to aforementioned gremlins.

Is it possible that it’s not junction box, fuse box or either front end earthing points ?
- instead simply a bad wire within the headlight harness ?
- or the wires connecting to the foot dipper switch ?

[Ron Kwas]

BLS;

Again, compliments on you detailed presentation of findings.

Comments:
1. Finding and replacing a defective bulb is certainly a good start...
2. Lighting (other than Instrument) is not fused, so likely not involved in causing the "gremlins"...but knowing Fuses and FB are in good shape is good associated info...
3. ...as is knowing general state of connections along the way...
4. ...and chassis connections certainly also look good (ideally, I would prefer to see the ACZP used on connections to know that they will stay electrically without developing series resistance as corrosion increases with time)...don't forget also, that the base of bulbs is in the chassis connection circuit, so must be without a series resistance. (Shown well here: https://www.sw-em.com/Amazon_Rear_Li...estoration.htm ) ...reminder: This connection is indeed as important as those screws into the bodywork!
5. OK...and the fact that it hasn't changed symptoms means we must keep looking, taking and considering troubleshooting findings...I will revisit the initial description more carefully...are you able to make voltage measurements with a Voltmeter? I might need to move onto power-up measurements at some point in the TroubleShooting process...

Answers to your Qs:
"- instead simply a bad wire within the headlight harness ?"...Possibly I suppose, but in general, wire (if not externally and mechanically insulted), does not go bad...terminations/crimps etc. develop resistance and eventually opens with MUCH higher frequency...
- or the wires connecting to the foot dipper switch ? Again, it is always important to keep an open mind during TS (lest we be shown to be foolish once the root cause is finally found, and we have previously unequivocally discounted it...) so I wont say it is impossible these could be involved (note my use of "wiggle-words" like "unlikely" and "probably", etc. during explanations), indeed if you have a Full-Beam signalling relay installed (an alternate source of power onto the Red Wires), the circuit does increase in complexity, and this must be taken into account during TS...

See also this thread with Simon's very good explanation of current paths during a fault condition caused by probably poor chassis connection (never confirmed, but consistent with symptoms and intermediate findings): https://www.volvoforums.org.uk/showthread.php?t=257267

Good Hunting!

[BLS07]

Cheers Ron!

Shall press on.

Voltmeter on order, as figured it may be required if not this time definitely another!

Recollection of symptoms in lead up to current state (pardon the pun!)

- recall newly installed (interim) foot- dipper switch get a bit sparky (electrics smelt at the time) at Grey wire input due to the original crimp being worse then I thought. I immediately changed and re-crimped to a new ring connector more aptly fitting the Brookhouse foot-dipper switch.

Wondering if that sent something of a bad charge up the circuit ?

Anyway, I’ll check the connections as you’ve described.

Will put some ACZP on order this evening, too.

Feedback soon.

Cheers!
BLS