No rear fog light on 1998 V70 R AWD. Topic is solved

Pentacyl · Post by **Pentacyl** » 23 Oct 2018, 13:45

Hallo! I'm a just-joined newbie. Please indulge me.

My wagon is coming up for it's annual inspection and I've found that the rear fog light isn't working. The switch light illuminates, I've metered the lamp and it's OK. I've removed and metered the 10A fuse, in/out of holder and it's also OK. All other lights work fine.

The local main dealer suggested replacement of the main light relay #3523200. It's the green one, under the panel in the general fuse box. It's a 'double' relay, A104 & E108. They can't confirm if that includes the rear fog light...!?

I've come across a 213/#9148992, black, regular size relay, below the steering wheel/instruments panel, on the right hand side of an RHD. It controls the fog lights. Again, I'm unable to get confirmation if that includes ALL fog lights or just the front?

There's a further relay, #9441161, listed as a Multi-Purpose relay. On eBay it's listed as a rear fog light relay. Again, not had much help from main dealer on eiher its function or location in the wiring.

Has anyone any ideas on how to resolve my problem, please?

Post by **erikv11** » 23 Oct 2018, 17:16

Turn the switch on, go to the back with your voltmeter and see if you can find 12V there. Look for corrosion in the socket, it is common.

Pentacyl · Post by **Pentacyl** » 24 Oct 2018, 04:23

Hallo and thank you, erikv11.

I have actually done all the basics, checked for corrosion, wiggled/removed sockets and whilst there's 12v everywhere at the rear light clusters, there's zero potential on the rear fog line. Must be a relay but which and where...?

Post by **BEJinFbk** » 24 Oct 2018, 08:27

There’s no relay. If the switch illuminates when you turn it on,
that indicates that power and ground are both present at the switch.
Power leaves the rear fog switch on pin 4, the violet/white lead, and
runs through fuse 25 in the “C” box back to the fog light. Is that fuse OK?

Pentacyl · Post by **Pentacyl** » 24 Oct 2018, 10:27

Hallo and thank you, BEJinFbk.

That IS an eye opener. No relay for goodness sake, what do these dealers know!? I shudder to think.

I'm a photographer but have been tinkering with cars a lot of my spare time. I came back to Volvos after a 40 year absence, when I bought this one last year. Love it but how things have changed! My previous ones were ace 145s and 245s but a divorce closed that chapter...

Back to the matter in hand. The reason I went searching down the relay route, is the main dealer. I think they wanted to make a quick $162.00! Unfortunately for them, I'm a bit long in the tooth to splash out willy-nilly.

To answer your post, yes, I've checked the fuse, both in and out of the housing and it's good. But I didn't check for potential ACROSS the fuse. If there's nothing there, does that point to a faulty switch? Equally, if there is flow across the fuse, would that indicate a break in the violet/white lead? What do you think, please?

I'm unable to check right now as my wife has the car and not back until late. I'll gt to it tomorrow and revert.

Cheers, Pentacyl.

Post by **BEJinFbk** » 24 Oct 2018, 15:05

I usually check for voltage when the fuse is in place.
Look for 12 volts on the two metal nibs on the top of
the fuse. If you have voltage on one side, but not the
other, there's your bad fuse.

If there's nothing at all when the switch is active,
I'd suggest getting to the back side of the switch
and confirming voltage is leaving pin 4.

I'd be really surprised if there's an actual broken wire,
but there are a few connectors along the way.
This may help:

98 S-V70 Rear Fog Light.pdf: (478.56 KiB) Downloaded 378 times

Pentacyl · Post by **Pentacyl** » 25 Oct 2018, 18:49

Hallo, it's been a long day/night! Thank you for yours, Wednesday 24 Oct, 10:05 pm, including PDF.

First off, ref the PDF. I don't totally recognise the component diagrams when compared with what's
in my engine compartment/below dash. For example, the 'C' fusebox at top right, page 117. Mine has
no relays #105s & #107 nor the other box of 15 relays, beneath the 'C' box itself. Also the
disposition of the contacts on the rear foglight switch #3/58, differs from mine. Mine run as follows,
with cable colours:

#1 – Blank
#3 – Yellow.......#2 – Brown
#5 – Black........#4 – Purple/White
..................#6 – Blank

Unfortunately, I've not had time to check the circuitry as yet.

I've however, carried out an extensive continuity and voltage check. The results are baffling!
It's quite complex so please bare with me. The checks were done in two stages, one with the
'C' fuse #25 out of the, the second with it in the circuit. These were subdivided into a further
two sections, 'Continuity' and 'Voltage'. The RHS & LHS fuse contacts are as seen with the fuse
numbers the right way up. The engine was running throughout.

FUSE OUT
– Continuity, switch #3/58 in OFF position.
All power off..............RHS fuse contact to switch contact #4..........Contact OK
...........................LHS fuse contact to switch contact #4..........No contact
Ignition at II–)...........RHS & LHS to #4................................No contact
Headlights off.)

– Continuity, switch #3/58 in ON position.
Ignition at II –)..........RHS fuse contact to switch contact #4..........Contact OK
Headlights off/on).........LHS fuse contact to switch contact #4..........No contact

– Voltage, switch #3/58 in OFF position.
Ignition at II)............RHS fuse contact to switch contact #4..........Zero volts
Headlights on.)............LHS fuse contact to switch contact #4..........Zero volts
...........................Switch contact #2/Brown to ground..............13.3 volts
...........................Switch contact #3/Yellow to ground.............13.3 volts
...........................Switch contact #5/Black to ground..............0.10 volts

– Voltage, switch #3/58 in ON position.
Ignition at II)............RHS fuse contact to switch contact #4..........Zero volts
Headlights on.)............LHS fuse contact to switch contact #4..........13.1 volts
...........................Switch contact #2/Brown to ground..............13.3 volts

FUSE IN
– Voltage, switch #3/58 in OFF position.
Ignition at II)............Fuse to switch contact #4......................Zero volts
Headlights on.)

– Voltage, switch #3/58 in ON position.
Ignition at II)............Fuse to switch contact #4......................Zero volts
Headlights on.)............Switch contact #2/Brown to ground..............13.1 volts
...........................Switch contact #3/Yellow to ground.............13.1 volts
...........................Switch contact #5/Black to ground..............0.10 volts

I made this check, twice and found same results. Something is wrong...

Look forward to hearing, Pentacyl.

Pentacyl · Post by **Pentacyl** » 25 Oct 2018, 18:53

Oh, dear, I should have reviewed that last message

Can do, please just ask

Friday, 26 October. I have edited previous post but it's still a bit scrappy. Apologies, there's a mismatch in the SW.

Post by **scot850** » 25 Oct 2018, 21:26

I know it sounds really simple, but have you tried just changing the bulb? I have had a few occasions where the bulb may show continuity but didn't actually work. Swapped the bulb and all was good.

Neil.

Pentacyl · Post by **Pentacyl** » 26 Oct 2018, 03:44

Hallo scot850.

Thank you. I haven't changed the lamp but just held it in the holder in reverse position and it's good.