ECU and ignition relay

From CEM to VEM, from LED to lightbulb and more. If you have an electrical problem, like a broken info-centre, search for answers in this category. This is also the place to be when you expect the problem to be of an electrical nature...

Moderators: jifflemon, coyote1980, Rachel

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

ECU and ignition relay

Post by andyb2000 » Sat Feb 16, 2019 7:29 pm

Hi all,

I'm still working on electrical problems on my 480ES 2.0 1994, the problem is a relay that clicks in and out rapidly, as though when it energises it gets a short somewhere, releases tries again and does this erratically.
It seems to stop after a minute of the ignition being turned on, seems related to the lambda sensor light going out. Whilst the relay is clicking the lamba also flickers, I also see the rev counter stutter a little (just bounce off 0). Does that rev counter stutter point to power being cut/dropped then back on? (Rest of ignition lights don't dim/go out).

The relays (two) that click are the ignition on and the fuel pump (The two relays under the steering column). I've tested/checked the relays and they're not at fault. I've also disconnected the fuel pump at the pump end to eliminate that (new pump on anyway).
So I'm now working through disconnecting sensors and wiring connectors to try and find the one that stops it. My guess is a bad ground/earth fault causing it somewhere.
My first thought was the lambda heater/sensor itself, so took battery tray out and took both connectors off for lambda (2-pin for the power to heater and 1-pin spade for the sensor data). No difference. I've then started to disconnect every sensor I can get my hands on. I've marked the sensors I've disconnected on the diagram to give you an idea!
I've also disconnected the whole ABS module (big pin connector block into the abs control module) to eliminate anything there.

I'm still getting the clicking. Can anyone come up with further suggestions on what to disconnect and more importantly where in the engine bay as I've had trouble locating a lot of items (despite having haynes, but it's not very accurate as we all know!).

Image

I've also removed/tested all the relays in the under-bonnet triangle!

Cheers in advance!
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

Alan 480
480 Is my middle name
Posts: 986
Joined: Sun Aug 28, 2011 9:03 am
Location: Aberdeen

Re: ECU and ignition relay

Post by Alan 480 » Sun Feb 17, 2019 7:06 pm

andyb2000 wrote:
Sat Feb 16, 2019 7:29 pm
It seems to stop after a minute of the ignition being turned on, seems related to the lambda sensor light going out. Whilst the relay is clicking the lamba also flickers, I also see the rev counter stutter a little (just bounce off 0). Does that rev counter stutter point to power being cut/dropped then back on? (Rest of ignition lights don't dim/go out).
just a VERY long shot, it MIGHT then be an issue with the dash board. if there is a dicky 12V supply/ground then rather than taking whatever should be the correct route for 12V or earth it going via the dash-board

this is a possible a complete red herring?

i'd pull the dash board out, clean contcats and re-insert, after all youv'e ripped every thing else out, including your hair :-)
Alan

480 ES 2litre x 2, C30 1.8ES, SS1

User avatar
brinkie
480 Expert
Posts: 624
Joined: Mon Apr 21, 2014 11:20 am
Location: The Netherlands
Contact:

Re: ECU and ignition relay

Post by brinkie » Sun Feb 17, 2019 8:20 pm

This may look like a silly question, but does your engine start?
I have had the same issues, all caused by a dead (well, almost) battery...
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

Re: ECU and ignition relay

Post by andyb2000 » Mon Feb 18, 2019 8:05 am

Thanks guys, yeah already was on the way to losing my hair, this is helping!

Already had the dash all out, did a solder reflow on it as the infocentre was dead, replaced bulbs and got that back up and lighting up. Good point though, it does 'feel' like a bad earth/live somewhere. I've cleaned the two grounds I know about (Under battery tray and to the left of engine on the top), are there any I've missed?

On battery, it's a known good battery, I can't start as fuel pump isn't running due to relay issue, but it will turn over on starter so juice is definitely there!
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

User avatar
jamescarruthers
480 Is my middle name
Posts: 1709
Joined: Mon Jul 07, 2003 3:19 pm
Location: Cambridge

Re: ECU and ignition relay

Post by jamescarruthers » Mon Feb 18, 2019 8:32 am

A 480 with a poorly battery clicks like crazy on attempting to start. How about connect another car via jump leads in parallel?
1987 Volvo 480 ES, 507274, 217 - Red (Ness)
2001 Volvo C70 2.4T convertible (Olivolvo)
2008 Mini Cooper convertible (Mau)

Previous 480's:
J123 CFU -- ES
J449 MNL -- ES auto
D864 CPV -- ES
L691 JFC -- Turbo
F70 MNR -- ES
H858 FGV -- Turbo auto
E981 KHM -- ES (509849)

User avatar
brinkie
480 Expert
Posts: 624
Joined: Mon Apr 21, 2014 11:20 am
Location: The Netherlands
Contact:

Re: ECU and ignition relay

Post by brinkie » Mon Feb 18, 2019 8:44 am

By the way, the info centre *is* a red herring. You can start and drive a car without the instrument cluster fitted at all, only the alternator won't charge the battery as the charging is "ignited" through the battery light bulb and/or the 120 ohm resistor. There is no CAN bus linking all components in the car, there are three (four if you have ABS) separate and independently operating computers. Many functions aren't operated by a computer at all, they're just relays and some logic. (Although some of the computers are running on specially crafted annoyatrons)
Robert.

Present cars: 1994 Volvo 480 GT 2.0i Vase Green, 2010 Volvo V70 2.0F Momentum Mystic Silver
Past: 1981 Talbot-Matra Murena 2.2 Rouge Mephisto, 1995 Volvo 480 GT 2.0i Paris Blue

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

Re: ECU and ignition relay

Post by andyb2000 » Mon Feb 18, 2019 10:23 am

Thanks! Battery has been charged and jumped to another (good idea) and still the same.

I think what's happening is similar to a low battery current situation though which sounds about right, hence my thinking its poor ground/supply causing them to clack away.

So mine has ABS, I disconnected the ABS module to eliminate that, so I know about the engine ECU (Driver side panel under dash), the BCM (Passenger side panel under dash) which other one am I missing? This is the 2.0L (non-turbo) B20F engine.
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

User avatar
jamescarruthers
480 Is my middle name
Posts: 1709
Joined: Mon Jul 07, 2003 3:19 pm
Location: Cambridge

Re: ECU and ignition relay

Post by jamescarruthers » Mon Feb 18, 2019 11:49 am

Have you checked the earth braid between the negative battery terminal and the engine? It runs under the battery tray, connects to the body then connects to the engine/gearbox.

Do the terminals or wires to/from the battery feel hot after a good crank of the starter?
1987 Volvo 480 ES, 507274, 217 - Red (Ness)
2001 Volvo C70 2.4T convertible (Olivolvo)
2008 Mini Cooper convertible (Mau)

Previous 480's:
J123 CFU -- ES
J449 MNL -- ES auto
D864 CPV -- ES
L691 JFC -- Turbo
F70 MNR -- ES
H858 FGV -- Turbo auto
E981 KHM -- ES (509849)

Alan 480
480 Is my middle name
Posts: 986
Joined: Sun Aug 28, 2011 9:03 am
Location: Aberdeen

Re: ECU and ignition relay

Post by Alan 480 » Mon Feb 18, 2019 12:44 pm

If engine happily spins over then it can't do any harm running a live feed to the fuel pump, it runs (should)100% of the time anyway so I'd 'hot wire' the pump, then try cranking it over, at least you could 'jury rig' a relay from the ignition supply to start / stop the fuel pump as a stop-gap? (assuming it will fire up)
you will need the main engine ECU to get it running, I guess the others cannot be damaged by 'not being connected' ?

can't think of an easy way to jury rig a way to get the sparks at correct timing, even approximately from the front of cam shaft .. . ..
Alan

480 ES 2litre x 2, C30 1.8ES, SS1

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

Re: ECU and ignition relay

Post by andyb2000 » Tue Feb 19, 2019 9:23 am

Actually Alan, you might have something. I might be trying to be too "proper" with my fix trying to track it down. Might be worth doing that and getting the engine running again as once that's running I'm more motivated to get the rest of the car ready. Aiming for summer to have her back on the road.

(Also just a thought, DRL's, they're both working but they're ignition so again poor earth, live, etc. Also is the relay that's hidden behind the front bumper, driver side the DRL relay?)
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

Alan 480
480 Is my middle name
Posts: 986
Joined: Sun Aug 28, 2011 9:03 am
Location: Aberdeen

Re: ECU and ignition relay

Post by Alan 480 » Tue Feb 19, 2019 12:43 pm

andyb2000 wrote:
Tue Feb 19, 2019 9:23 am
Actually Alan, you might have something. I might be trying to be too "proper" with my fix trying to track it down. Might be worth doing that and getting the engine running again as once that's running I'm more motivated to get the rest of the car ready. Aiming for summer to have her back on the road.

(Also just a thought, DRL's, they're both working but they're ignition so again poor earth, live, etc. Also is the relay that's hidden behind the front bumper, driver side the DRL relay?)
black square box about fag packet size? mounted vertically?

I think that is for the 'dim-dip'

lights are ALL on the panel above your feet when driving
Alan

480 ES 2litre x 2, C30 1.8ES, SS1

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

Re: ECU and ignition relay

Post by andyb2000 » Tue Jul 02, 2019 9:38 am

It's been a while but I'm still trying to get progress on this.

Yesterday I got a charged battery onto it, reconnected all connectors, ECU, etc.
I jumpered the fuel pump relay under the dash (When jumping this relay, the other ignition relay clicked and so did another one somewhere in the engine bay, couldn't identify which), but now the pump is running constantly.
Tried to start and although the starter is turning the motor over nice and quickly (no bad voltage drops so doesn't suggest insufficient power) it just turns over constantly. Did that a few times to see if it would even cough but nothing at all.
Am I right in thinking on the B20F 2.0 injection engine the engine ECU (driver foot side) controls the spark timing and injector firing? I'm suspecting more and more that it's the ECU that's failed here.
Going to test for spark when I get a chance next (Correct my thinking. Pull central lead off disty cap and shove spark plug in there and ground spark plug body. See if i get sparking which shows the HT and signal is working. From there I then check disty). After that, what else, are the injectors a signal I can test for firing with multimeter, see if I'm getting a pulsed voltage perhaps?
Any other suggestions before I try and get my hands on a B20F ECU replacement and try again?

Thanks in advance, am starting to think this one might not live again :-(
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

jifflemon
480 Is my middle name
Posts: 1128
Joined: Sat Dec 17, 2016 11:03 am

Re: ECU and ignition relay

Post by jifflemon » Tue Jul 02, 2019 9:40 am

have you checked the crank sensor is working?

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

Re: ECU and ignition relay

Post by andyb2000 » Tue Jul 02, 2019 11:34 am

Not yet, will add that to my list to check.
Crank sensor, two pin and check for resistance in ohms, also clean, check connector, etc?
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

Alan 480
480 Is my middle name
Posts: 986
Joined: Sun Aug 28, 2011 9:03 am
Location: Aberdeen

Re: ECU and ignition relay

Post by Alan 480 » Tue Jul 02, 2019 11:41 am

jifflemon wrote:
Tue Jul 02, 2019 9:40 am
have you checked the crank sensor is working?
need to check it isn't open circuit at sensor (unplug at bell housing) and confirm 'correct resistance' which I do have a note of, not at work though :-)

then plug it in & out a few times, might be a dicky connection? it can be traced back at the othe rend but the connector would be first stop.

is it stinking of fuel, plugs wet, that way you'd know that injectors are opening/closing.

if no fuel , maybe that's injectors?, they pulse so fast you'd NOT see with a meter, but maybe get a change in voltage, from ignition off, to ignition on , to engine spinning etc

try putting a teaspoon of petrol into inlet tract (just where throttle body is, if it coughs, then no signal to injectors?? but an't see all four failing :?
works on old carb fed engines!!! :D
Alan

480 ES 2litre x 2, C30 1.8ES, SS1

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

Re: ECU and ignition relay

Post by andyb2000 » Tue Jul 02, 2019 11:50 am

Thanks,
Yeah I'd not really thought of crank sensor, but sounds next one. Note I have here is 200Ω for sensor, so will see what I get. Thinking about it, that's the one sensor I've not disconnected/checked and could be causing my whole world of problems if it's faulty since it also controls fuel pump trigger, etc.

Was also thinking along the same lines with a can of easy start into the intake, see if it coughs to give a sign of life to see if fuel is there or not. Didn't notice a smell of petrol in the engine bay after various attempts and turning over, but my thinking is if the ECU isn't happy/getting the right triggers then it won't be firing the injectors either.

Thanks chaps, got a few things to try tonight then and see what I can discover.
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

User avatar
jamescarruthers
480 Is my middle name
Posts: 1709
Joined: Mon Jul 07, 2003 3:19 pm
Location: Cambridge

Re: ECU and ignition relay

Post by jamescarruthers » Tue Jul 02, 2019 12:05 pm

I thought you might just see the RPM needle dance when cranking over as a way of seeing if it is transmitting something?
1987 Volvo 480 ES, 507274, 217 - Red (Ness)
2001 Volvo C70 2.4T convertible (Olivolvo)
2008 Mini Cooper convertible (Mau)

Previous 480's:
J123 CFU -- ES
J449 MNL -- ES auto
D864 CPV -- ES
L691 JFC -- Turbo
F70 MNR -- ES
H858 FGV -- Turbo auto
E981 KHM -- ES (509849)

jifflemon
480 Is my middle name
Posts: 1128
Joined: Sat Dec 17, 2016 11:03 am

Re: ECU and ignition relay

Post by jifflemon » Tue Jul 02, 2019 1:06 pm

andyb2000 wrote:
Tue Jul 02, 2019 11:50 am
Was also thinking along the same lines with a can of easy start into the intake, see if it coughs to give a sign of life to see if fuel is there or not.
I hate that stuff - its WAY too flammable has has been known to knock out the upper rings; Which then makes starting harder, so you use more easystart.... Vicious circle.

Alan 480
480 Is my middle name
Posts: 986
Joined: Sun Aug 28, 2011 9:03 am
Location: Aberdeen

Re: ECU and ignition relay

Post by Alan 480 » Tue Jul 02, 2019 5:08 pm

jifflemon wrote:
Tue Jul 02, 2019 1:06 pm
andyb2000 wrote:
Tue Jul 02, 2019 11:50 am
Was also thinking along the same lines with a can of easy start into the intake, see if it coughs to give a sign of life to see if fuel is there or not.
I hate that stuff - its WAY too flammable has has been known to knock out the upper rings; Which then makes starting harder, so you use more easystart.... Vicious circle.
or bends the con-rods on a diesel as 'too vicious' , so it lowers compression and funnily enough, refuses to start on diesel :shock:
Alan

480 ES 2litre x 2, C30 1.8ES, SS1

andyb2000
480 Newbie
Posts: 38
Joined: Wed Sep 12, 2018 12:04 pm
Contact:

Re: ECU and ignition relay

Post by andyb2000 » Wed Jul 03, 2019 7:05 am

Ok, so general consensus is no to the easy start! (Was a mechanic friend that gave me the idea)

I was out last night, checked the crank sensor, removed it and cleaned it.
Ohms reading looks good to me:
Image

So that one I think is good. Next one is the ground behind the engine, I looked all over and couldn't spot it, anyone got a pic or an illustration of where it is as I believe it's key for the ECU ground?
Tonight I've got more time so will check spark, fuel, etc.
Thanks for all your help! - Andy
Volvo480 ES 2.0 petrol - 1994 (UK RHD L-reg)

Post Reply