Reverse lights after manual swap Topic is solved

[RobTheModd]

Vehicle - 1998 S70 T5 Manual Swapped. 

Main Issue - Reverse lights never got wired up when swap was done years ago.
Current Issue - Reverse lights still not working once wired up over the weekend.

Items checked / Things done - 
​​​​​​​I've wired the reverse light switch from the switch to the blue/grey and blue wires.   (There are 2 solid blue wires, I've tried both)
Brand new reverse light switch. 
While in reverse, lights do not come on.  
Fuse (27?) is good. 



Things on the list to check.  
If Bulbs are good (I looked at them and they seem good but ill go buy 2 new ones just because, unless someone can recommend an LED upgrade.) 
Resistance at switch (planning on checking during the week) 
Resistance / Voltage on the blue/grey - blue wires.  
Possibly tossing the old switch back in to try that. 



Looking for help on the issue, what else should I be looking for or at to try and remedy the issue. 

[abscate]

Pin 1 of witch 3/10 on top of the M56 should be 12 VDC hot whenever key is in POS II

Check there, and then that PIN 2 goes hot when you go into reverse.

After that, its a simple wiring fault between the 3/10 switch and the lights

See Main Forum Topics for guidance to wiring diagrams on the internet, not hosted here by legal agreement with Volvo

[RobTheModd]

Interesting, ill switch my wires around then as everything I was reading stated the switch polarity did not matter.
That could be my issue as to why im not getting lights as I was moving my ground and not my pos.

Which means I should be able to test which wire is hot while key in POS II to see if its the new switch even.

Gotta love Volvo, I forgot they requested everyone remove their wiring diagrams, had to pull them from our private forum years ago as well.

Thanks

[abscate]

12 VDC to Blue should light up the Reverse lights - if not, then there is a wiring problem downstream of the switch.

[RickHaleParker]

Things on the list to check.  
If Bulbs are good (I looked at them and they seem good but ill go buy 2 new ones just because, unless someone can recommend an LED upgrade.) 
Resistance at switch (planning on checking during the week) 
Resistance / Voltage on the blue/grey - blue wires.  
Possibly tossing the old switch back in to try that. 

Key must be in POS II for the Back-up lights to work.

Fuse 11A/4.
Relay 2/6 and signal from ignition switch (3/1).

3/10 & 3/71 are the back-up switches.
2/6 is the overload relay.
24/X are connectors.

If you are getting voltage at the Back-up switch 11A/4, 11C/27, 2/6, signal from ignition switch and connectors are good.

[RobTheModd]

Thank you both.
I'm going to put 12v to the blue wire and see what happens.

If nothing happens ill start in on the chain to see where the fault is starting with fresh bulbs.

[scot850]

As I have not owned an S70, are the back up lights in the rear cluster in the rear wings or in the trunk lid? If it is in the trunk lid then a broken wire at the trunk hinge is a probability.

Neil.

[RobTheModd]

As I have not owned an S70, are the back up lights in the rear cluster in the rear wings or in the trunk lid? If it is in the trunk lid then a broken wire at the trunk hinge is a probability.

Neil.

They are in the trunk lid.

[RobTheModd]

Update -

Ended up being the harness. 

Plug (pulled from a jy car) was falling apart so when I put it on the switch it pushed the connections out the back which I did not realize until last night.  
​​​​​​​Fixed it annnnd yep. 



Put 12v from battery to the solid blue for reverse and the lights came on so was able to quickly rule out the majority of the system. 

Reverse lights work perfectly now. 

Thank you for the help guys!
As I get the S70 all tidied up and ready for daily use for a couple months as I transition from a 2018 s60 to something new im sure ill be back with more questions, its been awhile since ive worked on the ol boy.