ecu wiring and electrical issues

mirage · Post by **mirage** » 07 Nov 2021, 02:23

I have changed my engine wiring harness on my s60r. The harness from a breaker came from an automatic car and I need to do some changes to the harness to check the wiring to the ECU. But I don't seem to locate the pins and compare them to the wiring diagram. any advise would be appreciated

Post by **firstv70volvo** » 07 Nov 2021, 13:36

mirage wrote: ↑07 Nov 2021, 02:23 I have changed my engine wiring harness on my s60r. The harness from a breaker came from an automatic car and I need to do some changes to the harness to check the wiring to the ECU. But I don't seem to locate the pins and compare them to the wiring diagram. any advise would be appreciated

I'm assuming your car has a manual transmission and I have a 2002 wiring diagram showing differences in the wiring harness between auto and manual cars and you can see there is a difference with the two data communications lines between the CEM of an auto vs. a manual car. If you have a wiring harness from an automatic car the two communications line go to the TCM connector where with the manual these communications lines go directly to the ECM. There may be other changes and there's also changes in the CEM and probably wiring diagram with 2005 and newer cars so none of this would likely apply for the newer models years cars.

auto vs. manual wiring differences.pdf: (130.75 KiB) Downloaded 792 times

mirage · Post by **mirage** » 09 Nov 2021, 10:33

Thank you for your input,as per your attached PDF the pins on the CEM are shown, please see the attached photo, I need to know how to identify they pins on the ECM so I can verify the wiring.

Thanks

Post by **firstv70volvo** » 09 Nov 2021, 10:49

mirage wrote: ↑09 Nov 2021, 10:33 Thank you for your input,as per your attached PDF the pins on the CEM are shown, please see the attached photo, I need to know how to identify they pins on the ECM so I can verify the wiring.

Thanks
IMG_20211101_162102.jpgIMG_20210907_134639_1.jpg

All I have is a photo of the TCM connector and I'm attaching it as it may be similar to the layout of the ECM pin connector. I can't tell from the photo if there's marking on the connector, there should be. Look for numbers at the ends of the connector rows and look for an A, B marking somewhere. Hope this helps some. If there's no visible numbers on the connector shown, look at the connector on the ECM for pin numbers at the end of the rows.

Not the connector for the ECM but the pin layout may help. Note the left end of the connector is not in the photo, there are a couple of more pins not in the photo and confuses the numbering sequence not seeing those pins.

: Screenshot 2021-03-18 124908.jpg (149.42 KiB) Viewed 7568 times

mirage · Post by **mirage** » 17 Nov 2021, 07:29

Thank you FirstV70 at least it seems my confusion is not unfounded, I have tried a few forums with no reply, your help is appreciated. I will use the photo and try and familiarise myself with the pins,

I thought 'A " was one of the rows.

Thanks.

Post by **firstv70volvo** » 17 Nov 2021, 08:13

mirage wrote: ↑17 Nov 2021, 07:29 Thank you FirstV70 at least it seems my confusion is not unfounded, I have tried a few forums with no reply, your help is appreciated. I will use the photo and try and familiarise myself with the pins,

I thought 'A " was one of the rows.

Thanks.

If the ECM connector follows the pattern of the TCM connector (photo) then you'll have two groups of pins A and B and you can see in the photo there's a dividing gap in the connectors between the A and B pin groups. The starting Pin1 location is different between the A and B pin groups and this may be the case with the ECM pin groups too but check for markings on the connector to be certain.

Post by **chrism** » 17 Nov 2021, 09:02

Can you pull the ECM connectors loose from the car in a way that you can see what wires are pinned to what connectors on the back sides of the connectors? Then compare that pinning arrangement to your old harness?

Also, is your car a manual trans? I think we are assuming that.

Do manuals have any sort of TCM?

Post by **abscate** » 17 Nov 2021, 14:16

Yes on the manual TCM, bu they are very expensive so most people take them with them when they leave the car. They don’t have a hold down, so you have to use the seat belt to hold them in place, too.

Ok, this is MVS Humour.

mirage · Post by **mirage** » 19 Nov 2021, 02:10

Thanks all, Looked under a magnifying glass and you can see the pin numbers and a and b connectors marked. (very vaguely)

Post by **RickHaleParker** » 19 Nov 2021, 08:40

mirage wrote: ↑19 Nov 2021, 02:10 Thanks all, Looked under a magnifying glass and you can see the pin numbers and a and b connectors marked. (very vaguely)

Take a felt tip marker and touch the marks very lightly. That will make the marking stand out. You want the ink on top of the markings only. You need to use a light touch so the ink does not get squeezed out of the tip and run all over. If the pen is in good condition the weight of the pen is uselessly enough pressure to transfer the ink without running. It is art so it takes some practice to master.