the glovebox comes right out, a few screws on the 'flange' behind the door and it lifts out, door and box as one piece. remove the footwell panel first for easier access.

the ICU is behind the glovebox, the ECU is on the right side of the footwell, just forward of the front door lower hinge. after removing the footwell upper panel (the grey felt one), then remove the black rubber trimstrip that goes around the lower front of the passenger front door opening and maybe a screw or two to remove the plastic side panel.

a bad ECT that reads too high of a resistance when its hot could cause hot-running problems, like too rich, or under/over advanced timing. the ECT has two sensors, one for the ignition timing, and one for the fuel injection mixture.

radio suppression relays are unique to 740/940's, 240's don't have them at all.

 

Thanks Pierce! I will take a look at it tomorrow or maybe day after and post back here

 

I found the ECU and ICU. Can't seem to find the PIN numbers? Can you please which way the numbers start?

Also the ICU only has 16 pins it. Remaining have no connectors inside them.

 

if you look inside the plugs (the side of the plug that goes onto the ICU/ECU), and shine a bright flashlight in there, the numbers should be molded into them. I can't say I remember how they go, I'd have to pull one apart to look.

and yeah, the ICU only uses that many, but the numbering counts every positiion, connector or not.

 

I tried looking. Couldn't find anything. The ICU on my car looks relatively new and is Bosch (even the plug). The ECU on the other hand is Bosch but the connector/plug is whitish and looks super old.

Is one of the LH 2.4 diagrams from page 1 relevant for me?
https://volvoforums.com/forum/volvo-...o-spark-72690/

You had posted it in 2013.

Edit: Here I found this on a 2012 post on this site http://volvowiringdiagrams.com/volvo...20Complete.pdf

Page 9 - correct? Now what about the ICU?

Page 37 onwards shows the ICU connector. But it shows only a single row of pins. I have 2 rows (although) the bottom row is only has 4-5 pins I think

 

yeah, LH 2.4 is pretty much the same in 240 and 740/940, 1989+ (turbo 1990+).

I don't think any of the diagrams I've seen, however, show the pin positions in the connectors.

 

I found the numbers for the ECU. Its on page 9 of the second link in my post. Its the ICU that's a little unclear.

I think you posted just when I edited my previous post.

 

ah. i have a newer version of that same green book that also covers the ezk ICU and doesn't show the connector layout, just the wiring diagrams

 

It looks like the coolant temp sensor is bad. Reading on the ECU were fine but on the ICU - with the engine warmed up was off the chart.

I am going to re-measure the numbers today or tomorrow afternoon (still don't know the number of the pins on the ICU- so measuring all permutations) and let me post back here.

How hard is it to change the ECT? Looks like it's one of those few parts that I can't get to by removing 5 bolts....

 

it just unscrews, but its probably a lot easier if you remove the intake manifold...

before replacing it, verify the cold measurement at the sensor (it has two pins, check each one to ground). your wild reading /could/ be wiring.

 

So I finally got back to the car. Couldnt do much the past few weeks after I dislocated my shoulder playing soccer....

anyways - I re-checked the numbers today. Something doesnt seem right. At cold engine (about 65-67F currently) - the ECU read 264 with the DMM set to 2000K and the ICU read 4.

Same readings when the engine was warmed up to operating temp.

When I started it up cold - it seemed to run a little rich. No codes stored though.

I have attached images of the pins with the numbers where I measured it. I re-checked the connectors for both ICU & ECU. Neither have numbering for me.

Also the connector on the block looks ok. The wiring loom looks untouched and has no exposed wiring as far as I could see.

 

you're reading this off the wiring harness plug (with car off and ECU/ICU unplugged), not off the ECU/ICU pins themselves, right?

it should be around 2300 ohms when its 67F

 

****!! No I was reading off the ECU/ICU pins themselves. These medicines really mess things up. Let me get the correct numbers. Probably going to be the day after - we have thunderstorms all day tomorrow.

 

Ok so measurements with the car parked outside for 48 hours (40-60F) is 2.71 ohms in 20K mode at ECU. 2.70 ohms in 20K mode at ICU.

Dropping DMM to anything lower (2000 or 20) results in the reading continuing to be a solid "1".

So is there a short somewhere in the system or is my ECT bad?

As I mentioned before the insulation at the connector on the block seems ok and not rusted/corroded

 

sure that wasn't 2.7 k ohms? which would be 2700 ohms? that would be the correct reading for a temp somewhere around 60F

 

At operating temp:
ECU - 297 with 2000 setting on DMM (0.29 at 20K)
ICU - 301 at 2000 setting (0.30 at 20K).

Is this a symptom of a short? What do I check next?

Edit: I just saw your message. Enlighten me on DMM usage. I assumed that at 20K it shifted to decimals (larger units from ohms - kilo, mega, etc). Is this correct? Do I need to remove the battery to check readings every time or can I directly connect the probe ends into the sockets?

 

DMM is a Digital Multi-Meter ... is that what you're using, or is it an analog VOM (Volt-Ohm-Meter) ? my DMM's read directly and display the actual units (like, k Ω for kilohms), they either autorange, or you set a fixed range (fixed range is useful to keep the decimal point from hopping around).

300 ohms, give or take (0.3 kΩ) is the correct reading for about 180F, which is typical operating temperature.

 

Mine is a VOM - analog with the dial in the middle to select V, R etc. Sorry for confusion - I thought they were all under DMM.

That's why I mentioned the 20K ohm mode and 2K/2000 Ohm modes that I was using while getting my measurement. So does that mean my readings are Ok and that the ECT & its wiring are ok?

 

can you post a photo of your VOM, sharp enough to read the scales ? its been quite a while since I've used one, but IIRC, depending on the scalar you choose, you have to use a different scale on the VOM, and yes, you manually have to scale it appropriately. like, if the VOM's display scale is 0-2000 and you've chosen a 20K range, you'd multiply your reading by 10.

but, yes, I think your readings are OK. 300 ohms hot, and 2700 ohms cold is definitely right in range. so the ECT is not your problem.

 

Here's a replica of what I have - http://www.harborfreight.com/media/c...mage_23327.jpg

So if the ECT values are OK - what else do you think could be causing this problem?

There are 2 things that may or may not play a role -

1. The end of the hose at the bottom of the idle control valve was chopped of by the PO. It sits tightly over the metal and I dont think it leaks.
2. There's a vacuum hose that goes from the front of the fuel pressure regulator to somewhere underneath it. That hose is loose on the FPR but it sits there fine.

Hate it when I try to do something preemptively and I am worse than where I started out.