B200F LH2.4 pin outs
 

Does anyone have a copy of the pin outs for the LH2.4 injection system on a 1990 740?

I have noticed a couple of times, that the idle sits too high - just over 1100RPM, I have checked the diagnostics and it records a 3-1-1 fault codes which appears to be speedometer signal missing so wonder if this is connected?

I have a copy of the LH 2.4 for the B230F engine on a 240 and this refers to a blue wire to pin 34 is this the same on the 2.4 fitted to the 740?

The only thing I have done recently is remove the dashboard to fit new panel lamps, I can find a blue wire and removed and refitted the plug to see if this cures it but is this the wire the manual refers to.

Thanks in advance.

Yes I have them, but not on my laptop. I am sure others will be able to give you a full rundown b4 I get there!! Have you got Haynes 2003 edition for the 700 Series it gives you some. Have a look at FAQ's above there are quite a lot there.

FYI - Although you might be reading a speedo fault it ain't necessary so. You are only say a few rpm above the norm 700/900rpm range. Blip the accelerator a few times and squirt some WD40 on the cable at the roundall in the engine bay. If no joy I would suspect the problem is a slightly gummed throttle valve ( again see FAQ's).

P.S. The blue wire? Can't recall that off the top of my head. Blue multi-pin plugs yes. Assuming you have a VDO cluster and the speedo needle is working you are getting a signal from the diff sender. So if there is a signal failure it will be from the back end of the cluster to the ecu. So pull them all again and clean with some switch cleaner.

Thanks bob12, I have a copy of the 2003 Haynes manual although it is very difficult to decipher the drawings in the back, and it labels it as LH2.2

If I switch the ignition off and back on the revs idle at normal and I've never had this fault code previously - plus the dashboard is the most recent thing I have disturbed so may well just need the contacts cleaning.

It mentions the blue wire in the Volvo service manual (green book) for the 240 I found on the net, which I why I wondered if it is the same. I don't know what signal the ECU expects to see.

I've cleaned everything up so will see how it goes, if not I'll look a bit further.

Genric LH2.4 info

Volvo Wiring Diagrams

Pin outs

These three should help

Idle speed control
 

The ECU only start to adjust the idle speed to 800-850 rpm when a) the accelerator is fully depressed (throttle position sensor) and b) if the speed is (almost) zero. So yes, when the speed signal is missing I can imagine the idle speed is not always set correctly.

well it is always a good rule of 'it was working until you did what...' so, still getting the speedo signal fault and high idle at time - didn't seem to do it all the time so took the dashboard out and checked all the connections again, it was only then that I noticed a connector that had dropped down the back. Checking the colour code of Violet and white, this tied up with the speedo signal to the ECU, so refitted it and hopefully this has cured the fault.

It was odd because I would give the car a short run round the block and the fault didn't seem to occur but did after a longer run, so perhaps there are a number of other parameters it needs to see as well.

Still, at least that's sorted.