Dear Fellow Brickboarders,

Hope you're well and stay so. Having cleaned the ground plates behind each headlight - using DeOxit and a fine abrasive - I continue to see the following:
(a) driver's side headlight is "dim"
(b) driver's side turn signal is "dim"
(c) passenger side headlight is "bright"
(d) passenger side turn signal is "bright"
(e) when headlight switch is set to "headlights", windshield wipers (front and rear window) turn on and run steadily, no matter the position of the windshield washer switch.

I wonder if the windshield wiper switch is internally shorted. I think it is the factory-original, so that switch doesn't owe me a nickel.

I welcome the benefit of your advice.

Stay well!!

Yours faithfully,

Spook

grounds and connections in cars/trucks are subject to corrosion.

to stop corrosion, use a special grease called NO-OX-ID. it is made by sanchem, inc and you can get it on ebay.

It was invented by the army in WWII. It is a conductive grease that will not catch fire (but it can smolder a bit). It is very resistant to being washed away.

I use it on all my car battery/alternator connections, grounds, and single wire connections. do not use it on multi-wire connectors.

ALL puzzling shorts I used to have (i.e. above) have stopped.

The 740/940 cars can have a grounding issue where the steering column is anchored to the dash board structure. It’s been know to cause electric signal back flow resulting in things like you honk the horn and the rear wiper turns on. Years ago someone on the BB named it the “horny wiper syndrome”.

Dim headlights on one side I've had like that before were a problem at the headlight connector. Any initial poor contact results in heat, promoting more oxidatioan, weakening of the thin contact fingers and ultimately deforming the pin holder connector. Peel back the boot and try pushing the wires in with the headlights on to see if things change. I know some have had to resort to cutting them off and splicing in a new connector. I seem to have caught mine early enough that I was able to clean things up, use a pin to pry the connector pins in for a snugger fit and finish by pushing the contact wires in from behind, making extra slack in the wires inside the boot so they don't want to pull out again. It took a couple of tries to get my cleanup to last more than a few months, the most recent effort has now lasted well over 5 years still with the original and slightly damaged connector.

The headlight switch making the wipers work of course smells like a short rather than a component or switch failure as there are few common devices and connections. Wiring shorts aren't common, but may happen where wires are badly pinched somewhere between metal. I'm thinking more along the line here of a poor ground connection in that headlight circuit that is resulting in voltage backfeeding into the wiper circuit in order to reach chassis ground, so I'd start by getting that headlight bright again. Backfeeding into the wiper circuit might also be caused by a poor contact at one of the headlight relays. A known problem area for high draw currents is the plastic sockets in the relay tray. After the headlamp connector is verified as okay, I'd next check under the tray, paying particular attention to the sockets and wires from the headlight relay (front row K), headlight flasher relay (2nd row, 3rd socket from left) and wiper relay (back row, 2nd socket from right). After visual inspections, it would be time to put a meter to work doing fault tracing on isolated circuits. The bulb out sensor relay is of course another common problem area. If you've got a spare or made up a bypass out of a bad one (as I keep on hand) then maybe try that before going to the effort of pulling out and flipping the relay tray.

I just saw Bulletproof's thoughts about broken tailgate wiring. 240's were definitely prone to this, but not 700/900 wagons with a different tailgate harness design. The exception would be a wire inside the tailgate chafing against a wiper linkage arm, but there are no headlight/park light circuits in the tailgate to short.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hello Dave,
Thanks for the post.
Which relay is the bulb out sensor relay?
Glen
--
Mine:3-940s running; 1-740, 2-940 parts; dtrs:4-940s running

I forgot about the big-red-round relay in the relay tray behind the fuses? Are they all the same? I have a box of 7 of them I had saved whenever a 740 or 940 went to the junkyard and had forgot about them.
Am I right that these are the sensor relays are all are the same?
I am having intermittent problems with my 1995 940 sedan. The bulb out dash lite comes on when the car is started and the goes out when the brake is depressed.
Than you once again - Glen
--
Mine:3-940s running; dtrs:4-940s running

Hi Glen,
Like Spook says, the bulb sensor relays are all the same, basically all the later 900/700/240s in the late 80s and beyond use the same sensor (the 3rd brake light becoming standard caused the changeover).

As far as your bulb indicator going out after touching the brakes, there's really only three likeloods.
1) If it's a KAE relay then absolutely swap in one of your others. I've had nothing but problems with two KAEs in my two '95 940s, and lord knows I've done enough swapping around, cleaning sockets and changing bulbs to convince myself they're oversensitive to something about my lighting systems.
2) Given your symptoms then more than likely, actually extremely likely, the relay currently installed is suffering from micro fractured solder joints. This so common it's almost laughable. Re-flowing the main (brake light) solder joints on the two tiered PCB boards inside the relay would almost certainly fix it. In yoir case with a box full of spares, just swap it out and put a felt penned ? Question on mark on the old and throw it back in the box.
3) Cleanup the brake light bulb sockets, including the 3rd brake light) and make sure the bulbs are the same brand and equally aged. This won't be your problem, but clean them up anyway niw that your working this area. If this was the only source of your problem then it would be different. The indicator would only be coming on when you touched the brakes.

I'm jealous of your box of spares. I'm using a bridged bad sensor in the car that needed the KAE, so no longer have the bulb sensor feature in that 940. Next time I trip over a cheap used Volvo one I'll grab it and restore functionality.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Dear jd620,

Hope you're well and stay so. The red cylindrical bulb failure relays are "all the same" insofar as 940s are concerned.

Hope this helps.

Yours faithfully,

Spook

This is off the wall and probably will not help but I will throw it out here anyway.

A bad tailgate ground in my '89 240 wagon caused some similar electrical weirdness. It was something like if the headlights/taillights were on and I would step on the brake the rear wiper would start. It also affected whether the third brake light would display or not. New ground wire; end of problem.


--
'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

Hi Spook,

Hope you're well.

Shooting from the hip I think your ground plate might not be properly grounded (to body). Need to remove that 10mm bolt and clean underneath. And your wiper switch might be faulty too.

I'll study the wiring diagram and continue later. Need to finalise autopsy report this morning.


Amarin

Hi Spook,

That's a funky failure.

Is the idiot light for the bulb out sensor OK ?
Does it act the same with high beams ?

Try pulling the left low beam fuse 19 and see if the wipers run with the
headlights switch.

Bill

Dear B.B.,

Hope you're well and stay so. Thanks for the suggestions!

The "bulb-out" warning light does not stay on after start-up.

I didn't test to see if high-beams work and if malfunction persists. I'll try that.

I'll also pull fuse 19 and see if the wipers still run non-stop, when the headlights switch is "on".

I'll report results.

Yours faithfully,

Spook

Hi Spook,

* Besides reporting on what happens when you pull Fuse 19.

You can measure DC volts at the top of ATC Headlight Fuses
Use cigar lighter ground.

with low beams on:
drivers low beam fuse 19
passengers low beam fuse 20

with high beams on:
driver high beam fuse 17
passengers high beam fuse 18

Did you say the lights are all dim on the driver side.
Is that all lights: Hi, Low, Parking, Turn signal?

* Your failed and repaired front driver side ground, 31/2 needs to be tested.

An easy way is to disconnect the negative battery terminal and
measure between pin 4 (ground) of the drivers headlight connector
and the negative battery cable end with your ohm meter.
Use your lowest scale and read close to zero ohms.

Headlight connector Pins 1 and 2 should not show any continuity to
pin 4, and the battery negative cable end using the highest resistance scale.

Report back, Bill

Hi Spook,

It's hard to see how the headlight switch can run front and rear wipers,
and this is a single connected problem. They're on separate fused circuits.

Is your washer pump buzzing too when this happens?
You can isolate the problem some more by removing:
Fuse 15 front wipers
Fuse 14 Tailgate wiper

The circuit diagram shows 3/12 as the front wiper switch
with an intermittent relay 2/4
There's a an inset showing interconnected junctions for the wiper stalk
switch in 5 different positions. You could check with ohmmeter
and 3/13 as the tailgate switch
with an intermittent relay 2/16

Firewall connector C2 is in series with all this stuff, you could eyeball
the harness to see if it looks healthy. I would not unplug it.
You could easily get in the soup and have a big job on your hands.

Amarin, Does the bracket between the high firewall and the strut stud
(that the connectors including C2 are tie wrapped to) do they get released
by just removing the nut from the rear strut stud?

I'm in the middle of repairing the OBD port A & B with the silicone support
for the female pins fragmented and only a few recognizable pieces left in the
collection of debris that fell out. Dave Barton has the parts needed to fix.

The OBD port has bullet connector style pins. Beware taking them apart
since you may be stuck reassembling them. The RSR has this style connector
so there's a landmine to know about.

Amarin, Brickboard mail is kaput, how do I e-mail you with off topic music stuff?

Bill

Hi Bill,

"Does the bracket between the high firewall and the strut stud
(that the connectors including C2 are tie wrapped to) do they get released
by just removing the nut from the rear strut stud?"

No. The strut bracket is welded in place. FYI the C2 connector (53-pins) is located cabin side, not engine. In my RHD car its on the left side behind the glovebox. In US cars it might be on the left side of steering behind dashboard


"How do I e-mail you with off topic music stuff?"
Email me at: pperubfor@gmail.com

Amarin

Hi Spook,

It's hard to see how the headlight switch can run front and rear wipers,
and this is a single connected problem. They're on separate fused circuits.

Is your washer pump buzzing too when this happens?
You can isolate the problem some more by removing:
Fuse 15 front wipers
Fuse 14 Tailgate wiper

The circuit diagram shows 3/12 as the front wiper switch
with an intermittent relay 2/4
There's a an inset showing interconnected junctions for the wiper stalk
switch in 5 different positions. You could check with ohmmeter
and 3/13 as the tailgate switch
with an intermittent relay 2/16

Firewall connector C2 is in series with all this stuff, you could eyeball
the harness to see if it looks healthy. I would not unplug it.
You could easily get in the soup and have a big job on your hands.

Amarin, Does the bracket between the high firewall and the strut stud
(that the connectors including C2 are tie wrapped to) do they get released
by just removing the nut from the rear strut stud?

I'm in the middle of repairing the OBD port A & B with the silicone support
for the female pins fragmented and only a few recognizable pieces left in the
collection of debris that fell out. Dave Barton has the parts needed to fix.

The OBD port has bullet connector style pins. Beware taking them apart
since you may be stuck reassembling them. The RSR has this style connector
so there's a landmine to know about.

Amarin, Brickboard mail is kaput, how do I e-mail you with off topic music stuff?

Bill

Hi Spook,

It's hard to see how the headlight switch can run front and rear wipers,
and this is a single connected problem. They're on separate fused circuits.

Is your washer pump buzzing too when this happens?
You can isolate the problem some more by removing:
Fuse 15 front wipers
Fuse 14 Tailgate wiper

The circuit diagram shows 3/12 as the front wiper switch
with an intermittent relay 2/4
There's a an inset showing interconnected junctions for the wiper stalk
switch in 5 different positions. You could check with ohmmeter
and 3/13 as the tailgate switch
with an intermittent relay 2/16

Firewall connector C2 is in series with all this stuff, you could eyeball
the harness to see if it looks healthy. I would not unplug it.
You could easily get in the soup and have a big job on your hands.

Amarin, Does the bracket between the high firewall and the strut stud
(that the connectors including C2 are tie wrapped to) do they get released
by just removing the nut from the rear strut stud?

I'm in the middle of repairing the OBD port A & B with the silicone support
for the female pins fragmented and only a few recognizable pieces left in the
collection of debris that fell out. Dave Barton has the parts needed to fix.

The OBD port has bullet connector style pins. Beware taking them apart
since you may be stuck reassembling them. The RSR has this style connector
so there's a landmine to know about.

Amarin, Brickboard mail is kaput, how do I e-mail you with off topic music stuff?

Bill