So I'm trying to get a 240 running that's been sitting for a few years, and I noticed a blue electrical connection/wiring harness on the positive battery lead that isn't connected to anything. I know there's a 25A fuse also on the positive lead that is for the fuel injection, so I'm thinking this may have something to do with my problem (starts and idles fine but stalls when put into gear). Anyone know what this is for and what's supposed to be connected to it?

 

what year 240 is this?


stalling in gear suggests an issue with the idle air controller, or with the ignition timing, but thats really hard to say without knowing the year as there's at least 3 different fuel injection systems over the 20+ years of 240's.

most later years, there's 3 wires at the + terminal. the really fat one goes directly to the starter, and on to the alternator. the 25A inline fuse is, as you say, the fuel injection power (but in some years, this is in the fuse panel). then there's another moderately heavy (6 mm^2) wire that runs to the 'positive terminal' on the left fender under the hood, which is where most other powered stuff is connected including the ignition switch.

 

It's an '86. Here's a picture, it doesn't actually connect to the positive terminal but it runs down into the engine along with the line that the 25A fuel injection fuse is on.

 

Looking at it now I think it might be a return line from the alternator, because I had to jump the battery and left it idling for about 15 minutes so it would charge back up, but I tried to start it later and it was dead as a door nail.

 

the blue wire off the alternator is the alternator ground. without it, the alternator won't deliver any significant charging current. one end should be on a stud on the back of the alternator thats connected directly to the alternator body, the other end should be on a ground bolt on the engine block

 

So what you're saying is I need to get a connection from the blue wiring harness in the pic and ground it?

 

Nevermind, I see what you're saying. So the blue wiring harness is not the alternator ground, which leaves me back at square one.

 

that blue /connector/ is, I believe, for a remote start switch. it should have a blue-yellow, and a pink wire, and if you connect a pushbutton switch to it, it lets you run the starter while working on the engine. <= only partially correct, see below.

the blue wire in the upper left of your pic, with the red sleeve on it, that looks to me like the alternator ground wire I described above.

 

Maddenkm, that blue connector is supposed to be hanging there all by itself. It is used as a test port- a jumper wire placed in each side to make continuity puts the engine in a particular mode, IIRC All the LH 2.2 cars have them. It's not something commonly used; I recall only once I had to use it; perhaps adjusting the AMM. If I can get to my Bentley manual, I can tell you more. Just know that that is not your problem.

 

It's called the Lambda-Sond test point

 

This is kinda off topic but...

Your 1986 Volvo is among those model years that had wiring harness issues.

Here's a link with more info...

Dave's Volvo Page - Volvo Engine Wire Harnesses

 

Yeah I read about that, but mine seems to be ok. Thanks

 

ah, right, the blue-yellow wire comes from the ECU and is the lambda-sond test signal. you connect this to a duty cycle meter and at idle, if the O2 sensor is working well, should see about 50% duty cycle

the pink wire is starter override like I described, you need a starter button that connects the pink wire to battery + to manually trigger the starter.

 

So after closer inspection is it seems like my wiring harness is in fact shot. Is it a bear to switch it out, and could you point me towards a good tutorial?

 

Dave Bartons website is THE source for wire harness issues.

The FAQ is at the bottom of the page...

Dave's Volvo Page - Volvo Engine Wire Harnesses