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ECU Swap/Repair 1996 850R

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

wackenhut
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Year and Model: 850R 1996
Location: FLORIDA

ECU Swap/Repair 1996 850R

Post by wackenhut »

If I am having issues starting the car and the last resort is to check the ECU, is this something that can be swapped out without any issues? How do you remove the ECU and where is it located? I was just wondering if an ECU is specific to each car.

Thank you.
yanga001
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Re: ECU Swap/Repair 1996 850R

Post by yanga001 »

swap is 1:1 for another 850 R Ecu. What issue are you having? (for newer cars it is not 1:1)
1998 S70 N/A Auto (Parts car)
1998 V70 N/A Auto New Daily
1998 V70 N/A Auto (Workhorse) (Tree to driver B pillar :( )
1999 S70 T5 Auto(Project)
2000 S70 SE M Learning platform
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Re: ECU Swap/Repair 1996 850R

Post by yanga001 »

Stupid suggestion as per pm, but did you try replacing the ignition coil? Ive had a v70 that would go from hard cranking to no start since we fried the coil. Replacing it let it start like nothing. If a wire is frayed there (super rare, but your car seems to be a special case) it might not let it start at all although you did mention its a no start so the starter must be going. Only other thing i can think of is a ground fault causing the voltage to drop. Coil could do that or other main power components.
1998 S70 N/A Auto (Parts car)
1998 V70 N/A Auto New Daily
1998 V70 N/A Auto (Workhorse) (Tree to driver B pillar :( )
1999 S70 T5 Auto(Project)
2000 S70 SE M Learning platform
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RickHaleParker
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Re: ECU Swap/Repair 1996 850R

Post by RickHaleParker »

wackenhut wrote: Thu Nov 12, 2020 8:43 am I was just wondering if an ECU is specific to each car.
Hardware is going to be the same you have M4.3 vs M4.4. The ECU is not tied to the car but there are different versions of software for different configurations.

The ECU/ECM is under the hood, in the black box on the right side. You will need a ECU tool to unlock it from the socket. , or , Remove the sides of the box and slide the locks on both sides with a small screwdriver or something else you can push the locks with.

You can learn a lot at M44 Wiki. Including how to copy and transfer your R software to new hardware.
Last edited by RickHaleParker on Thu Nov 12, 2020 9:10 am, edited 1 time in total.
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD.
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
yanga001
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Re: ECU Swap/Repair 1996 850R

Post by yanga001 »

I do not think the pre 99's need a tool, i recall they have a switch on them that desockets and slides them out. (might be wrong)
1998 S70 N/A Auto (Parts car)
1998 V70 N/A Auto New Daily
1998 V70 N/A Auto (Workhorse) (Tree to driver B pillar :( )
1999 S70 T5 Auto(Project)
2000 S70 SE M Learning platform
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RickHaleParker
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Re: ECU Swap/Repair 1996 850R

Post by RickHaleParker »

yanga001 wrote: Thu Nov 12, 2020 9:09 am I do not think the pre 99's need a tool, i recall they have a switch on them that desockets and slides them out. (might be wrong)
Went out and took a peek at my 1998 C70. You are correct the M4.3 & M4.4 have a release lever on each unit. It the ME7 and beyond that need the tool. Guess some CEO at Bosch wanted the cost of the release levers to pay the mortgage on house #3 .
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD.
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
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erikv11
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Re: ECU Swap/Repair 1996 850R

Post by erikv11 »

There is no ECU tool needed (or even produced) for a 96 850. You can swap in any USA market T5 ECU 95-98, it can be an R ECU or not. You may get a CEL for not having matching emissions equipment but it will start the car. I'd get an m4.4 ECU.

To copy and transfer your exact R software to new hardware is not routine at all, I don't suggest getting into that unless you are already skilled at programming. However flashing a spare ECU with a generic R tune is pretty easy. These points can be investigated at the wiki that Rick referred to.
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 293k
'06 S60 R, 167k
'07 XC70, 170k
'99 Camry V6 :shock: 130k
gone: '96 NA 850 210k, '98 NA V70 182k
wackenhut
Posts: 185
Joined: Tue Jul 07, 2015 9:32 pm
Year and Model: 850R 1996
Location: FLORIDA

Re: ECU Swap/Repair 1996 850R

Post by wackenhut »

Does anyone have a spare ECU that I can put in my 1996 850R to see if that fixes the intermittent no start issue? As long as it is just a quick plug and play replacement to test and see. If it requires any compatibility issues to deal with etc, this option does not make sense.

Thank you.
Chuck W
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Re: ECU Swap/Repair 1996 850R

Post by Chuck W »

I have a couple '96-'97 "Turbo"/T5 ECUs that will drop in and run your car. (From a '96 or '97 non-R HPT)
'97 854 T5 - Manual Swap, M4.4,COP, P2R Brakes, 16T, chassis bracing, XC70 nose swap
'97 855 GLT - Hers. RN swap/16T/exhaust/302s/Flashable M4.4, chassis bracing, 2 kid seats
'78 GLE - Waiting in the wings. Future whiteblock/T5 swap.
wackenhut
Posts: 185
Joined: Tue Jul 07, 2015 9:32 pm
Year and Model: 850R 1996
Location: FLORIDA

Re: ECU Swap/Repair 1996 850R

Post by wackenhut »

I would feel more comfortable swapping the same year and “R”.

I have a whole discussion on my car:
Issue with 96 850R Starting Not Turning Over

Just wanted to prepare myself should the positive battery cable replacement not fix the issue.

Thank you.
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