Hi fellow Volvo'ers

The relays are running real hot on a lot of Volvo's from reports I have read on internet, and including my two Volvo 940's ... this is a summary of trouble-shooting and maybe you guys have additional input to get to the bottom of this issue, because this can burn the car down...

I have two 940's.. both have similar issue and my friend noted his 940 actually CAUGHT ON FIRE with same issue. This seems like a common problem.

Here are the Volvo's...





The green 940 started smoking the other day on interior cabin, pulled the ash tray and cigarette lighter tray out and found the headlight relay "K" being extremely hot and it hat melted the female socket for "K" headlight relay.

Now .. why is the relay getting so hot it is melting?






I replaced the "K" headlight relay with two other relays from other Volvos and they all were getting hot...

I also replaced/tested other 'bulb out relays' shown below, to eliminate that being the issue of 'bulb out relay' shorting.



It is clearly melting because there is a lot of heat, which is caused by resistance, which is caused by a poor connection and possible arcing occurring...

The fuses are NOT getting hot or blowing... just side note.



Port 30 on headlight relay socket is always hot, with current coming straight from battery with no fuse in-between. The fuses are after the relay.

I then used multimeter and checked for ohm resistance in port 30, and found 4.5 ohms of resistance in port 30 of the relay female socket. I cut the positive wire below the female socket's connecting gullwing pin, to get a raw feed of resistance from wire (maybe the melted/corroded gullwing pin was causing resistance), but there was still 4.5 ohms of resistance.

My dad has another 940 Volvo identical, so I asked dad to test his and he was getting 0.5 ohms of resistance in port 30, versus my 4.5 ohms of resistance...

I then pulled a new high quality silicon coated automotive wire directly from battery to port 30 and re-wired with new gullwing connector pin at port 30, to make sure the resistance is brought down and everything is as good as it can be.

I tested the alternator if it is not overcharging, and was getting 13 volts from (brand new) battery with ignition off and 14.something volts with ignition on, and the voltage was not fluctuating with fluctuating RPM's so the voltage regulator appears to be working properly.

I drove for 2 hours and felt relay heating up still.. now the relay is getting so hot that I can touch it barely, but it is still uncomfortably hot... previously it would be melting plastic after 1 hour of driving. Clearly new wire brought some resistance down and eliminated some heat.

Also noticed that the headlight relay heat fluctuated as I am driving. One interesting observation was that headlight relay and seat heater relay (to the left of headlight relay) both were real hot, and then both in tandem got cooler and then hotter again... leading me to speculate they have a common grounding, which is poor and not grounding properly? Can that be the case?

I then took out the red 940 for a drive to see how hot the headlight relay gets, and the 940 headlight relay now gets hotter than the green 940 relay. The red 940 relay gets so hot I am unable to keep my finger on it for more than 1-2 seconds. .. both cars have same issue, but they are just short of melting the relay/socket.

Had dad test the identical 940 Volvo at his disposal, and after running for 30 minutes, the headlight relay did not get hot at all. When he put high-beams and low beams (his words) on, after 10 min the relay got so hot it was uncomfortable to touch it for more than 20 seconds... but that is far away from my both cars where I can only hold my finger on relay for 1-2 seconds after 30 minutes of driving with low-beams , and he can hold finger for 20 seconds with high-beams/low-beams. Note: He has US spec headlights (versus my euro-spec) in otherwise identical US Spec 1994 940 Volvos. Both my Volvos have Euro-spec headlights. This should not make a difference because all bulbs are 55w.

Question is, what is causing this extreme heat in the relays? Relays should not be getting hot enough to melt plastic.
Do they have common grounding, that is poor and causing resistance?

Please check your Volvos 700/900's how hot your headlight relay gets. This is a common issue and I want to find out how many are affected and get to the bottom of this issue and fix it, because this is a fire risk.

In order to remedy the issue for now I bought fire extinguisher for both cars...



With relays this hot, they are just below melting point and all the car needs is slightly poor connection in the headlight wire/connector somewhere to make that extra resistance/heat and it will start melting plastic or burning down the car... that is why I'm trying to get to bottom of this issue, figure out why everything is running so hot.

Do NOT want the Volvos to catch on fire suddenly and burn down, you know...

The K relay powers both the low beams and front fog lights (high beam uses another relay). I would isolate the relay circuits to know which have greater load on the relay. Disconnect the specific lights at their electrical plugs within the headlight enclosure as the E-code healights uses 4 in 1 plug harness connection. Or you could pull the fuses. Fuses #19 and #20 for low beams, #7 for both front foglights. Test each circuit separately. See if the relay still hot.

Another alternative is to start using LED bulbs for the low beam/foglights. Phillips (Lumileds) and Osram offer quality LED bulbs that closely mimics the point source of light as halogen bulbs (to avoid blinding the drivers of oncoming cars). Look in eBay. They draw much less current (less watts) with brighter output.

I'm currently using LED bulbs so my K relay just slightly warm.

Amarin.

I have a suspicion the ground for the K and other relays is weak. The reason is that the "seat heater relay" that is to the left of "headlight relay", both fluctuated in heat at same time, both were real hot to touch, then got cooler, then got real hot again... my suspicion is that they have common ground. Must research further, though...

The grounds for the K and heated seat relays are the same (also other relays too) - they all connect to a ground bar under the relay cluster shelf itself. This bar ultimately connects to the main ground tab at bottom of A-pillar within front passenger footwell. You could remove the bottom plastic trim of the pillar to get access to this main ground.

There are several ground wires going to the same main ground - hard to tell which actually from the relay cluster. Pull them all out, clean those gound tabs and insert all back.

I think you suspected poor grounding causing poor relay latching - thus weak relay contact point closure - causing those extra heat. It could also be the relay itself - worn internal contacts - due to ageing. Use spare unused relay if you have one - good to stock some. Or could borrow the other car's K relay. Or get a new one.

New metal body K relay is hard to come by these days. Try your luck at eBay or FCP Euro.

Amarin.

Dear Amarin,

Hope you're well. Volvo VADIS - a superseded dealer parts/service database - shows that the "K" relay is part #1324749. This item is available from a U.S.-based Volvo dealer for about US$35.

FCP Groton (www.fcpgroton.com) supplies a Bosch part (#0332015006) apparently identical, for about US$14 (See: https://www.fcpeuro.com/products/porsche-saab-volkswagen-volvo-multi-purpose-relay-bosch-0332015006#fitment ).

While FCP lists the above-noted Volvo part number as the equivalent
to the Bosch part, FCP's list of vehicles accepting this relay does not include Volvo 940s.

As parts can suddenly become "no longer available" - and this relay is a mission-critical part - having a new spare "on hand" surely is a good idea.

Hope this helps.

Yours faithfully,

Spook

I tried three different relays from three different cars... all the relays were overheating to where it is not feasible to touch them.

I tried three different 'bulb out' relays as well to rule out the possibility of them going bad...

I appreciate all of your guys expertise and will check ground contact by the passenger footwell.


Also, bought a stock relay at electronics store, supposedly same function as K in the car, but when I plugged in the relay from the electronics store, the headlights stayed on in 'power off' position of light switch.

The other relays sourced from other 700/900 Volvos, worked fine, but still heated up.

Out of curiosity I installed back my H4 halogen bulbs. YES the K relay runs VERY hot - unable to touch for more than 2 seconds after car running for 10 minutes. Using infrared thermometer the relay's metal body temp is 156F. The J relay next to it runs 128F but I don't have heated seats as this is tropical car. And I've cleaned my main ground tabs about a year ago.

So I think your concerns are legitimate but this is still normal. No plastic melting around my relay socket. My relay shelf/socket came with the car 24 years ago. The relay's plastic shelf should be able to withstand those temp anyway. 156F is way below 212F (water boiling temp) so its still acceptable. Also along those years I have used higher output H4 bulbs (150% more light output from Philips) and still no melting there.

I think your melted port 30 connector is an issue limited to itself - increased wire crimp resistance over time. You could go under the relay shelf to solder the wire to its connector for lower resistance. Do this for other high current connectors especially for fuel pump relay.

I switched to LEDs about 6 months ago to compensate for ageing headlight reflectors. And they perform about 300% brighter than halogen - even with old reflectors. The K relay is just warm to touch.

Amarin.

What worries is me what is causing it get so hot, because technically due to it being so hot we have no "reserve"...

A poor contact between relay and the incoming relay wiring's gullwing clips on fuel pump or headlight or other high output relay and plastic starts melting because it is already so hot, a poor contact would push it over the edge of melting, just like it did on my green Volvo. I will see if I can find a infrared temp measure gun and measure my relays in near future.

I had another guy with identical red universal Volvo 940 report that his headlight relay gets just as hot.

Looks like I will be switching to LED. What is the brightest LED that I can fit in there?

Still the fuel pump relay is an issue...
Also, weird that your heated seats relay heats up when you don't have such.

These are standard LED H4 bulbs:

https://www.ebay.com/itm/Philips-H4-6000K-X-treme-Ultinon-LED-High-Low-Beam-Headlight-Lamp-160-Bright-B1/264104636394?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D20160323102634%26meid%3Dd9a971289ade4b08bced6f85423ce105%26pid%3D100623%26rk%3D2%26rkt%3D6%26sd%3D302716509926%26itm%3D264104636394&_trksid=p2047675.c100623.m-1

These show reasonable brightness so as not to attract undue attention from traffic enforcement officers into thinking you're running some kind of racing setup. They are 17watts each compared to 55watts halogen. The relay should run cooler. The non-standard ones are many in eBay mostly from China.

Amarin.