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DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

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

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matthew1
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Volvo Repair Database DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by matthew1 » Wed Dec 19, 2012 3:52 pm

[The following text and photos were sent to me by MVS forum member gchelidze. gchelidze, sorry for the long delay in getting this up onto the forum, and thank you for the tutorial.

Note: this is a little more involved than "normal" -- there is no "eject" lever on this modules, so gchelidze takes the case/box off to get to them. If your Volvo's TCM or ECM has a lever, once you take the top of the box off, pull the lever and your TCM or ECM will come out. No need to remove the whole box as shown in these photos. -- Matt]


TCM step by step removal how to Volvo S70, 1999, 2.4 non-turbo

WARNING: I have done this procedure twice - once with battery lines connected and once with negative line disconnted. I didn't see any difference. However I would disconnect it if I have to do it again just in case. Do it with your own risk! If you decide to disconnect a negative line from a battery, make sure you have a your audio system unlock code. You will be prompted for it after you connect a battery back again.

1. Tools you'll need: hex socket M10, screwdriver, thin metal stick (pic 00.jpg)
2. Location: TCM is located in a black rectangular box at front right side with yellow sticker on it (pic 01.jpg)
3. Unplug two tubes from the front (pic 02.jpg)
4. A cover is locked from the left and right sides with two locks. Unlock them with a screwdriver and take off the cover (pic 04.jpg)
5. Inside a black box you can see a ECM and TCM from left to right (pic 05.jpg)
6. Locate a screw in the front and unscrew it (pic 03.jpg, pic 06.jpg)
7. A black box is locked from the front, right and back sides using three locks. Unlock them with a screwdriver and slide it up (pic 07.jpg)
8. Now you have a better view of both control modules (pic 09.jpg)
9. Look behind the control modules and you will see four pink plastic locks, two for each control module (pic 10.jpg)
10. Now you have to unlock the TCM. This is the most trickiest part. Before you start, please take a look at pic 12.jpg to get a better idea about locks. Press pink plastic locks with a thin metal stick from back to front in turn. Don't press them too firmly or you will break something. Do it step by step (left, right, left, right, so on). You will need 4-5 tries before it's fully unlocked. When you are done, you can pull the TCM out from it's socket (pic 11.jpg)
11. Next two pictures clarify why you need to press pink plastic locks in turn (pic 13, pic 14)
12. That's it. If you reached this point, you have done the job.

I'd like to mention a couple of things to easily put everything back:

13. If you look under the white socket you'll notice two pink plastic locks which you already pressed from back to front. You have to press them in opposite direction to lock the TCM (pic 17.jpg)
14. After you have locked your TCM, you need to place a black box back. Pay attention to slides (pic 19.jpg, pic 20.jpg)
15. Make sure that an air flow tube is sitting correctly at the back side (pic 21.jpg)
16. lock all three locks on a black box, put a screw back (pic 22.jpg)
17. Final steps: put a cover back and lock it, plug plastic tubes and you are done.
18. Start your engine and make sure you do not have a check engine light nor flashing arrow on your dashboard (pic 23.jpg)


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These users thanked the author matthew1 for the post (total 2):
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1997 850 T5, MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace [gone]
2004 V70 R [gone]

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Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by sjbock1 » Sat Dec 29, 2012 12:39 pm

Great photos and instructions. BUT....as a long time Volvo owner (83 240 GL and 94 850-original owner) and "newbie" at doing my own repairs on the 850, I find it very frustrating when posters of car repair information on the internet use initials and don't ever identify what the initials stand for. For instance it took me quite a while to figure out what NA stood for (normal aspiration/non turbo model which is what I have).

On this page, I am unable to determine what ECM and TCM stand for. I was looking for information on cleaning/replacing my ECT, Engine Coolant Temp Sensor. Is the ECM related to that?

Thanks.

Sandra

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matthew1
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Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by matthew1 » Sun Dec 30, 2012 3:44 am

Hi Sandra,

ECM definition and TCU definition found in the Volvo Glossary.

If you run across a term that should be in there and isn't, please contact me and I'll add it.
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1997 850 T5, MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace [gone]
2004 V70 R [gone]

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goVolvo
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Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by goVolvo » Tue Jan 20, 2015 1:06 am

Silly question, what is the name of hose from fan shroud to the TCM? I managed to break it when installing my fan. Is it for cooling the TCM using natural air flow? The intake opening of this hose is before the fan and radiator. My hose is broken at the corrogated section. Is it Ok just glue and wrap them together?

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Ozark Lee

Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by Ozark Lee » Tue Jan 20, 2015 8:14 am

My hose is broken at the corrogated section. Is it Ok just glue and wrap them together?
Tape is fine.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

esl_97_850_T5
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esl_97_850_T5

Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by esl_97_850_T5 » Fri Jan 23, 2015 12:16 am

I taped my mess of holes in the corrugated section with aluminum tape (Scotch 3M Foil Tape 3311). I've rewrapped it once in 2.5 years.
1998 Volvo S70 GLT - 205.5K miles - S70 & M44 testbed in 2016-2019; traded 2019-07-15 (for spare time)
1997 Volvo 854 T5 - 147K miles - 850 testbed in 2012-2017; junked 2017-09

Ozark Lee
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Ozark Lee

Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by Ozark Lee » Fri Jan 23, 2015 7:53 am

Necessity being the mother of invention, this is my version of the 99+ ECU removal tool.
ECU Removal Tool.jpg
It is long enough and thin enough to walk the ZIF socket retainers in or out by catching the purple retainers at the back. I go from side to side a little bit at a time until the retainers are either fully released or locked. It helps to rock the ECU a bit side to side as you walk it in. When removing the modules you can use a small screwdriver to push the rails back from the front side.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

GeoLoder
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Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by GeoLoder » Tue Mar 31, 2015 2:48 pm

These are great instructions and it work great. I matched the OEM part number to a used ECM I purchased. How do I pair the replacement ECM with my car? My car doesn't start with the replacement ECM, but as soon as I put the old one back in, it starts right up. Is there a procedure to pair a replacement ECM with my car? Can I DYI or do I have to go to a dealer?

Ozark Lee
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Ozark Lee

Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by Ozark Lee » Tue Mar 31, 2015 7:02 pm

If you are referring to a '99 module the module is coded for your car and only your car. You can't just plug and play a replacement.

I won't say that it is impossible to do it yourself (there are some cloning programs out there and you need to build up an interface) but the path of least resistance is to send the modules (both the source and the target) off to ARD or Xemodex and have the existing programming from your car transferred to the replacement module. ARD is by far cheaper, particularly when you factor in that Xemodex wants $70.00 to stick them in a box and mail them to you, and I just like the service from ARD.

If you are comfortable with burning ROMs I can try to dig up some of the links for the cloning software and hardware. I might try it just to see how it works now that I have a spare cloned module to work with and I won't risk killing the car completely if I fail. I was reticent to do it myself when my original module was the only thing between me and at least $1500.00 from the dealership to sell me a new module and do the software uploads to it.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

Richard_TD
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Richard_TD

Re: DIY access/remove ECM & TCM on 850, S70, V70, XC70, C70

Post by Richard_TD » Tue Apr 07, 2015 12:35 am

Thanks for posting this. My fault finding had come to a halt because I really needed to get the ECU out. I'd probably have worked it out for myself in the end but it's always easier to do a job like that if you know what you are going to find.

After reading the guide I went out to see how easy it was to do. One thing led to another and before I knew it I had located and bypassed the broken signal wire that had disabled the turbo and caused the MIL to light (or would have if the previous owner hadn't removed the bulb).

I went a step further and released the white base from the black box. I wanted to confirm I was tapping into the right wire, and it's lucky I did because I wasn't. Having the base out also made it slightly easier to push the locks back at the end of the job.
1996 855 GLT 2.5 20V

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