Coil Wiring Cleanup

[stokesy]

Hello friends, I'm picking up the pieces from a failed ignition wiring harness repair. The tech ordered the splice kit and made some clean looking connections. I'm getting 12V on each coil connector, so far so good. He only labelled 2 of the connectors however, so I don't know which coil 3 of the connectors go to. I hear the wires are color-coded, does anyone know where I could find that color chart?

The tech seems to think he might've fried the ECU, would I be seeing 12V impulses on the wires if this was the case?

Thanks for any help.

[stokesy]

Car is 06 XC70 2.5L
They installed an EBay kit which is not color coded

[firstv70volvo]

Hello friends, I'm picking up the pieces from a failed ignition wiring harness repair. The tech ordered the splice kit and made some clean looking connections. I'm getting 12V on each coil connector, so far so good. He only labelled 2 of the connectors however, so I don't know which coil 3 of the connectors go to. I hear the wires are color-coded, does anyone know where I could find that color chart?

The tech seems to think he might've fried the ECU, would I be seeing 12V impulses on the wires if this was the case?

Thanks for any help.

Does the new wiring harness repair preserve the wire lengths to each coil connector so you can tell by the connector position which one goes to which coil? If not you'll need to verify coil connector pin to ECM pin number and I can help find his information if needed.

Check the photo in the link for the turbo car coil pins connections. Pin 1 is the coil on/off switching signal from the ECM, I'm not certain about the voltage levels on this pin but this pin drives a switching transistor so probably 0-5V, 5V on, 0V off and when spark is generated. Pin 2, is open, no wire. Pin3 is ground, larger black wire. Pin4 is 12V, green/white wire to all coils. What voltage do you measure on pin1 for each connector with the ignition on? 12V should be on pin4 for every connector.

some good info and photos here, turbo cars have three wires going to the coils
https://www.elbertbos.nl/5cylindercoilr ... sguide.pdf

[stokesy]

Does the new wiring harness repair preserve the wire lengths to each coil connector so you can tell by the connector position which one goes to which coil? If not you'll need to verify coil connector pin to ECM pin number and I can help find his information if needed.

Check the photo in the link for the turbo car coil pins connections. Pin 1 is the coil on/off switching signal from the ECM, I'm not certain about the voltage levels on this pin but this pin drives a switching transistor so probably 0-5V, 5V on, 0V off and when spark is generated. Pin 2, is open, no wire. Pin3 is ground, larger black wire. Pin4 is 12V, green/white wire to all coils. What voltage do you measure on pin1 for each connector with the ignition on? 12V should be on pin4 for every connector.

some good info and photos here, turbo cars have three wires going to the coils
https://www.elbertbos.nl/5cylindercoilr ... sguide.pdf

Much obliged, that's great info. I ended up using the very thorough Prancing Moose wiring chart. Turns out you really only need to know the colors of pin #1 wires as the others are power and common. The wires melted so badly that the pink and purple had turned to brown. So I had to tear the harness further back.

This is a lovely car so I'm happy to keep it in the living. Next up will probably be the propeller shaft as I hear some ticking back there...

[EngineeringBloke]

Be careful!

Be sure to route the coil wiring so that it is not crimped by the plastic top of engine cover. You can tell by placing the cover into place and feeling for any springiness due to trapping wires. Do this before bolting down. The cover should fit with a sense of 'rightness' and no friction.

If you crimp the wires, you can short them out! That would be a shame after doing a replacement.

I have not had the cover on for a few years as the top of my engine is hotter than I think it should be. I did crimp the wires once during a spark plug change but was lucky.

[XC70Rider]

Hello friends, I'm picking up the pieces from a failed ignition wiring harness repair. The tech ordered the splice kit and made some clean looking connections. I'm getting 12V on each coil connector, so far so good. He only labelled 2 of the connectors however, so I don't know which coil 3 of the connectors go to. I hear the wires are color-coded, does anyone know where I could find that color chart?

The tech seems to think he might've fried the ECU, would I be seeing 12V impulses on the wires if this was the case?

Thanks for any help.

Does the new wiring harness repair preserve the wire lengths to each coil connector so you can tell by the connector position which one goes to which coil? If not you'll need to verify coil connector pin to ECM pin number and I can help find his information if needed.

Check the photo in the link for the turbo car coil pins connections. Pin 1 is the coil on/off switching signal from the ECM, I'm not certain about the voltage levels on this pin but this pin drives a switching transistor so probably 0-5V, 5V on, 0V off and when spark is generated. Pin 2, is open, no wire. Pin3 is ground, larger black wire. Pin4 is 12V, green/white wire to all coils. What voltage do you measure on pin1 for each connector with the ignition on? 12V should be on pin4 for every connector.

some good info and photos here, turbo cars have three wires going to the coils
https://www.elbertbos.nl/5cylindercoilr ... sguide.pdf

Thanks for the coil repair diagram. I'll use the bottom section of page 4 to rebuild my ignition coil harness for the 2.5T on my 2007 XC70.

After replacing the spark plugs I got misfire on cylinder 3 after the engine fully warmed up in 4 miles. I pushed the connector back onto IGN coil 3 and made it back home. I zip tied the connector onto the coil nice and tight but it still misfires after a full warm up. The connector is in bad shape and the IGN coil connection clip is broken on top so it cannot clip back on. I loomed the coil wires 4 years ago but they're also towards the end.

I ordered 5 new Bosch IGN coils from FCPEURO, 5 wired pigtail connectors from EBAY, and shrinkable butt crimps from Amazon. I'll start a new thread next week when I rebuild the harness.

[cn90]

Also, I leave the cosmetic cover off (leaving on the TB cover on), this way I can inspect the coils with ease and
avoid trapping heat shortening the life of the wiring and coils themselves.

[XC70Rider]

Also, I leave the cosmetic cover off (leaving on the TB cover on), this way I can inspect the coils with ease and
avoid trapping heat shortening the life of the wiring and coils themselves.

I read that tip you gave in a previous thread so I have left the cover off for at least 2 years. It gets far too hot and is too tight for that harness.

[brianmul]

Hello All,

My 2006 XC70 has continued to have an intermittent misfire issue. Typically once every 2 or 3 weeks. Engine starts 'stumbling' from start (can be cold start or once driven) Ravely ever happs once the car is driving. Replaces the Plugs, Coil packs and Injectors (they had done 250k km and one was missing one of the o rings). Car drove fine for a few weeks, and the misfire is back again. I cleaned up and put new covers on the wiring harness last year. Only sing of fouling is at the back RH side behing the engine - photo attached. I'm not sure what this hose carries or if that could be the next thing to look at. Any advice would be well appreciated.

[jonesg]

how intermittent is it ? few times a minute ?
test the ignition plug for cyl 1, make sure its making good elec connection, try pressing it with your finger when its idling.
spray with electrical cleaner like de-oxit.

buy harness cover in any parts store, cut to length.