CEM Problems - Replacement unit needed, Help!

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...

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Nick1307
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CEM Problems - Replacement unit needed, Help!

Post by Nick1307 » Wed Aug 23, 2017 8:44 pm

I have just taken the plunge a brought my first 480, I have a 1989 1.7 ES. So far I have no indicators/hazard lights, heated screen, inside lights and Info centre is dead + main dash lights. Windscreen wipers work and all lights/pop ups.
The car dosent start and came with a new fuel pump, changed the relays but no difference - I will check the power supply this weekend to the pump.
CEM unit is reference is 434 379

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brinkie
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Re: CEM Problems - Replacement unit needed, Help!

Post by brinkie » Thu Aug 24, 2017 8:56 am

Nick1307 wrote:I have just taken the plunge a brought my first 480, I have a 1989 1.7 ES. So far I have no indicators/hazard lights, heated screen, inside lights and Info centre is dead + main dash lights. Windscreen wipers work and all lights/pop ups.
The car dosent start and came with a new fuel pump, changed the relays but no difference - I will check the power supply this weekend to the pump.
CEM unit is reference is 434 379
It could be a CEM issue, but then again, it could very well be something else, and the info centre not working could be completely unrelated! I would check ALL fuses first, and then check the earth from the CEM to the chassis. Also, take out the CEM itself (it is located on the left hand side next to the bonnet release), it is a bit of a pain to get the three connectors loose, but if you can open up the CEM (just 4 screws) you can quickly see if components are corroded and/or burnt out.

See the FAQ section of this website under 30 Electrical system, CEM, changing a CEM: http://www.volvo-480-europe.org/volvo480/faq/index.php

What is the VIN of your car?
Robert.

Present cars: 1994 Volvo 480 GT 2.0i, 1999 Volvo S70 2.5 Europa, 2010 Volvo V70 2.0F Momentum

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WRDendy
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Re: CEM Problems - Replacement unit needed, Help!

Post by WRDendy » Thu Aug 24, 2017 9:20 am

I had exactly the same problem in my '89 ES, no indicators, hazards etc and it turned out to be the CEM so it sounds like you are on the right track. There are a few cars being broken on eBay at the moment including a 1.7 so if they have a CEM 1 you might be in luck.

Also worth following Brinkie's advice about fuses and grounds, as well as checking the CEM. He normally knows what he's talking about!

Another person had the same problem in this thread: http://www.volvo-480-europe.org/forum/v ... =12&t=5228. Looks like it turned out to be a relay for him. Worth having a look inside your CEM to see if there's anything not working or burnt out - might be possible to repair/replace. There's a nice photo of the inside of the CEM in that thread as well:
Image
Formerly known as 'Jaster'
Current: '94 GT & '88 ES
Former: '89 ES

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dcwalker
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Re: CEM Problems - Replacement unit needed, Help!

Post by dcwalker » Thu Aug 24, 2017 9:24 am

I agree with what has been said above.

One particular earth to check is the small one running to the alternator bracket. There should be a brown wire and a blue wire running to a spade connector there and often this breaks. If nothing else, your infocentre won't work without it!

Good luck!

David
Current: 1994 480 GT, 1996 460 CD & 1997 440 LE with lots of optional extras & 2007 V50 SE Sport
Previous: Celebration 331 (re-homed with Richard S), Celebration 467 (returned to Martin Mc); Celebration 346 (re-homed with Alan480); Celebration 269 (scrapped abandoned project), Celebration 73 (sold on after 6 years), 1992 ES, 1988 ES - and numerous other non-480 Volvos!

Nick1307
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Re: CEM Problems - Replacement unit needed, Help!

Post by Nick1307 » Thu Aug 24, 2017 6:41 pm

Thanks for your replies, I have taken the CEM out apart from small amount of corrosion on the top right connector spades it all appears ok, nothing burnt out. The small relays all seem to be ok. Just got a voltage tester so will see if its getting any juice.

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dcwalker
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Re: CEM Problems - Replacement unit needed, Help!

Post by dcwalker » Thu Aug 24, 2017 6:56 pm

That's a useful start - clean off the rusty bit of connector though, however slight!

Keep us posted - these cars just require a methodical approach coupled with the patience of a saint at times, but we'll all help you get there if at all possible :D

David
Current: 1994 480 GT, 1996 460 CD & 1997 440 LE with lots of optional extras & 2007 V50 SE Sport
Previous: Celebration 331 (re-homed with Richard S), Celebration 467 (returned to Martin Mc); Celebration 346 (re-homed with Alan480); Celebration 269 (scrapped abandoned project), Celebration 73 (sold on after 6 years), 1992 ES, 1988 ES - and numerous other non-480 Volvos!

arthuy
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Re: CEM Problems - Replacement unit needed, Help!

Post by arthuy » Thu Aug 24, 2017 6:59 pm

check you are getting power at the fuses.

I didnt and it was due to the relay being faulty.

Nick1307
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Re: CEM Problems - Replacement unit needed, Help!

Post by Nick1307 » Thu Aug 24, 2017 8:28 pm

Ok, just put the voltage tester to work, on the CEM apart from the fifth pin from right on the bottom connector I have voltage on every pin. As far as relays in the CEM the only two that don't appear to do anything when actuated are the two top right. What I did find was that the rear wiper worked when the relay was connected, however the switch on the stalk dosent seem to do anything? all pins on the top of the CEM apart from the second from the right have voltage. Are the two dead relays the idicators/hazard ones?

Nick1307
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Re: CEM Problems - Replacement unit needed, Help!

Post by Nick1307 » Thu Aug 24, 2017 8:35 pm

VIN Number: 0490201V
XLBEX 143EKC 542979

arthuy
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Re: CEM Problems - Replacement unit needed, Help!

Post by arthuy » Fri Aug 25, 2017 6:24 pm

The 480 is little different to normal cars.

The other thing is that the relays are Type A which is less common, so worth checking you have the correct type fitted.

Image

This diagram is the five pin version showing the difference between the relay pins, but the 4 pins are the same without the centre pin (87a).

Does your hazard switch work the lamps?

amazontommy
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Re: CEM Problems - Replacement unit needed, Help!

Post by amazontommy » Wed Sep 06, 2017 3:23 pm

Got similar problems and I am going to swap the CEM. Can you put a ES CEM into a Turbo?

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dcwalker
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Re: CEM Problems - Replacement unit needed, Help!

Post by dcwalker » Wed Sep 06, 2017 7:48 pm

amazontommy wrote:Got similar problems and I am going to swap the CEM. Can you put a ES CEM into a Turbo?
Yes.

If not the car model that matters it's the CEM. There are three versions - everything post about 1991 is CEM III. As long as you replace like for like it will be fine.

David
Current: 1994 480 GT, 1996 460 CD & 1997 440 LE with lots of optional extras & 2007 V50 SE Sport
Previous: Celebration 331 (re-homed with Richard S), Celebration 467 (returned to Martin Mc); Celebration 346 (re-homed with Alan480); Celebration 269 (scrapped abandoned project), Celebration 73 (sold on after 6 years), 1992 ES, 1988 ES - and numerous other non-480 Volvos!

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brinkie
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Re: CEM Problems - Replacement unit needed, Help!

Post by brinkie » Wed Sep 06, 2017 7:54 pm

More precisely, if you have a Phase 2 car (smaller side mirrors, 60 litre fuel tank, VIN from 567600 onwards, January 1991 or later) your car is equipped with a CEM-III. Phase 1 cars have a CEM-01 or CEM-00 (the very first years). CEM-00 and 01 are more or less compatible, CEM-III is completely different!
Robert.

Present cars: 1994 Volvo 480 GT 2.0i, 1999 Volvo S70 2.5 Europa, 2010 Volvo V70 2.0F Momentum

amazontommy
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Re: CEM Problems - Replacement unit needed, Help!

Post by amazontommy » Thu Sep 07, 2017 6:25 am

Mines a -88 first year turbo. So if the item number match on the module it should work regardless if it comes from an ES?

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dcwalker
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Re: CEM Problems - Replacement unit needed, Help!

Post by dcwalker » Thu Sep 07, 2017 8:27 am

amazontommy wrote:Mines a -88 first year turbo. So if the item number match on the module it should work regardless if it comes from an ES?
Correct, yes. :D

David
Current: 1994 480 GT, 1996 460 CD & 1997 440 LE with lots of optional extras & 2007 V50 SE Sport
Previous: Celebration 331 (re-homed with Richard S), Celebration 467 (returned to Martin Mc); Celebration 346 (re-homed with Alan480); Celebration 269 (scrapped abandoned project), Celebration 73 (sold on after 6 years), 1992 ES, 1988 ES - and numerous other non-480 Volvos!

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brinkie
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Re: CEM Problems - Replacement unit needed, Help!

Post by brinkie » Thu Sep 07, 2017 10:17 am

Every ES from 1988 - 1990 will be a good CEM donor :)
Robert.

Present cars: 1994 Volvo 480 GT 2.0i, 1999 Volvo S70 2.5 Europa, 2010 Volvo V70 2.0F Momentum

amazontommy
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Re: CEM Problems - Replacement unit needed, Help!

Post by amazontommy » Sat Sep 16, 2017 4:07 pm

Swapped CEM but still runs poorly. Hard to start. Seems some like one sensor is not working.
Got new sparks, cables and ignitor. Where should I start troubleshooting? Disconnecting a sensor at a time and listen for changes? If there is no change it could be the faulty one. Or are there any suggestions?

Alan 480
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Re: CEM Problems - Replacement unit needed, Help!

Post by Alan 480 » Sat Sep 16, 2017 5:56 pm

amazontommy wrote:Swapped CEM

but still runs poorly.

Hard to start. Seems some like one sensor is not working.

Got new sparks, cables and ignitor. Where should I start troubleshooting? Disconnecting a sensor at a time and listen for changes? If there is no change it could be the faulty one. Or are there any suggestions?
Three topics?
CEM is for wipers/ lights hazards etc (assuming the one on LHS in PLASTIC housing, engine management unit is in ally housing on RHS.

for 'hard to start', bit more info would help . .. .
eg
does it spin over fast but not fire?
does it cough and not pick up?
does it start then die?

the idle valve can get 'sticky' and not modulate low engine speed, try looking in the throttle body and open a TINY bit and keep in that position with a bit of wire so that there is always some air getting in, I rebuilt engine and it was 'idling around 1500rpm, as the bolt holding idle valve to inlet manifold was missing as I'd not put everything back on oops

maybe things like throttle positon sensor not working,

air temp sensor iffy

whole miryiad of possiblites :eek:

you need a multi meter to check the resistance of the various sensors (and HBOL)

'run poorly'

if misfires then yes pull one plug-lead at a time (whilst running if REALLY brave wearing rubber gloves x2 and use insulated pliers) other wise stop between each plug lead, if no change on one cylinder then might be plug/lead or dizzy

or do you mean 'doesn't pull' properly?
Alan

480 ES 2litre 'Celebration' ? , C30 1.8ES, SS1

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