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LH2.4 Install/Conversion. Just 4 wires to make it run

ZVOLV

<Master Tech>
Joined
Nov 19, 2002
Location
California
LH2.4 Install/Conversion. Just a few wires to make it run

Right click dead links and open in a new window to view pics.

Do you want to know how to install Bosch LH2.4 EFI in your Volvo? Fantastic! It's very simple and only takes a few wires. We installed a 1994 B230FT and LH2.4 into a 1984 240 Turbo and this is how we did it.
Need:
-LH2.4 240 wiring harness.
-B230FT Engine OR drill/tap block for RPM sensor if attempting on a B21/23. If you don't drill/tap PERFECTLY the airgap will be wrong and it won't run at all/well.
-LH2.4 Fuel Computer and Ignition Computer
-LH2.4 Flywheel or Flexplate and RPM sensor
-Complete rear axle or differential from electronic speedo 240
-Electronic speedo cluster
-LH2.4 Idle air motor
-LH2.4 MAF
-LH2.4 Coolant temp sensor
-Greentop injectors and resistor pack OR high resistance injectors like 850 Turbo orangetops
-2 small Custom fuel lines if converting from Kjet OR fuel lines from an EFI car

Process:

-First remove old engine bay harness

-Install B230FT and transmission of choice

-Install electronic speedo rear axle with gear ratio of choice.

-Install LH2.4 engine harness, run it thru firewall, and hook up computers.


-There is a wiring pigtail that goes from the computers and across the dashboard. Updated Nov 2015. Colors may vary slightly by harness year. Make sure you do your homework! But here are the basic few wires to make the thing run. Again, this is using a 1989/1990 wiring harness. Dash pigtail is different on the later models. SLIGHTLY. Don't be a bonehead. Get out a multimeter and wiring diagram and figure out the differences.


Wire 1: Thicker (12ga?) Red/Yellow- Power OUT TO Fuel Pumps.
(Wire 2:) Thinner (16ga?) Red/Yellow: Power FROM fuse to Heated 02. (Vehicle will start without this wire connected)
Wire 3: Blue: Ignition ON signal.
Wire 4: Blue/Black: Signal fom back Speedo (optional. You will get high idle after freeway runs without it. No big deal.)
Wire 5: Power up ignition coil with switched 12v. ( i suggest adding it to 2 wire plug. One wire is yel/red. Other is blue. By adding 12v to this wire, you are powering up the coil and the powerstage)
(Wire 6) entire LH System/Fuel Pumps gets power from a RED fused wire from the battery. At least on 1989-1990. Later model wiring harness is different. Sort thru other guy's posts or look at wiring diagrams to figure it out.

- Relocate the MAF wiring to the other side. This was easy. We pulled all of the wires, except the brown/black ground wire, out of the harness carefully and moved them to the other side. For the ground wire (that black/brown) you cant pull it out because it grounds other things. You need to pull it out as much as you can and then attach it back to your MAF plug.

-Plug in 4 wire connector in your new 2.4 harness into the old firewall connector. Its grey.

-There are a few other wires that need to be hooked up for AC, ABS function, and Check Engine Light but the above wires are all it needs to RUN! Pink one is for Check Engine light BTW.

-For fuel lines you can either get a complete set of EFI fuel lines from a donor car, or you can have a custom feed line and return line made. We went to Parker hose fittings and got hooked up with both for about $20!

-SPEEDO. Considered optional. If you do NOT run a speedo signal, you may have moments of high idle. For the speedo signal you just need to install a electronic speedo rear axle, or attempt to install just the diff and diff cover in your existing housing. You will also need to install a electronic speedo cluster. There are two wires coming off the differential. You run the black wire to the same ground point with the black wire coming of the speedo. The blue wire from the diff cover goes directly to the instrument cluster. Then you need to hook up the red/black wire from the ignition switch to the back of the cluster. This will power the whole cluster up. Use the old wire that powered up your instrument cluster.
 
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Right click links and open in a new tab to view!!


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There is a medium sized grey plug (8 pin?) that connects at the center of the firewall. This plug at the firewall is compatible with the LH2.4 harness. Just plug it in! This gets you alternator excitor wire, starter signal wire, temp guage signal, and oil WARNING light. This also used to have your wires for the oil pressure guage. You need to hook those back up to your chassis plug here if you are trying to retain the 240T pressure guage.

This solid blue wire (cant really see in this pic) got a jumper wire (our yellow) attached to it and we ran it to the coil positive. This blue wire is the power for the coil from your old 240 kjet chassis harness. It should be sitting right there where you removed the old 240 ignition box from. You simply put a male spade on your jumper wire and plug it into the female plug on the blue wire. Then you simply add a male plug to your jumper wire and plug it onto the coil. Now your coil should get 12v when you turn the ignition on.

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Thank you for this guide. I do have a few questions.

Where do I get fuel pump power from if I didn't have an electrical fuel pump to begin with?

What do I do with the electrical speedo, seeing as how I have the early cluster in my car? Will the car not run at all without the electrical speedo signal? I have all the wiring from the rear axle (an electrical speedo 1031) to the computers but no way to run the speedometer itself. Maybe I could integrate it into the early cluster, replacing the original speedo?

What colour is the TPS wire that is to be cut?

Thanks again.
 
Thanks. Are there any pictures available of the LH 2,4 harness with all the connectors labeled? I forgot where some of them went and I was too stupid to label the harness as I took it out. My Haynes is of no assistance.
 
Thanks. Are there any pictures available of the LH 2,4 harness with all the connectors labeled? I forgot where some of them went and I was too stupid to label the harness as I took it out. My Haynes is of no assistance.


Those connector are color coded, and only place where you can do wrong is inder intake; temp sensor, idle motor and knock sensor. I can check my notes
 
I think I figured it all out, it really made sense seeing as how it was colour coded (except the white connector which fit on a black sensor under the intake mani) and routed in branches. I could however not identify a few odd connectors that stick out toward the drivers side headlight. They aren't the standard clip-on connectors.
 
I think I figured it all out, it really made sense seeing as how it was colour coded (except the white connector which fit on a black sensor under the intake mani) and routed in branches. I could however not identify a few odd connectors that stick out toward the drivers side headlight. They aren't the standard clip-on connectors.

They're not connectors for test equipment are they? Like for tuning your MAF sensor and all that.
 
These are the wires I was wondering about. The blue one, the red one and the one I'm holding. They're part of the same branch.

DSC00295-1.jpg
 
The blue and red/white wires are for the ignition coil. I'm not sure what that connector is, though-what sort of car did the harness come from?
 
That grey plug is tach signal to cluster and the power for the coil.


BLUE needs 12v switched (12v ONLY with key ON) and then the RED/WHITE goes to your tach.

Connect that blue wire to whichever wire powers your coil.

If you want to run a tach, you run that red/white wire to the back of the cluster and plug it in!

NOTE: When pulling a harness from a donor car, don't be a noob and cut the wires right at the plug! Cut AT LEAST 6 inches after the plug so you have the connectors and a pigtail lead.
 
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Thanks. I don't need the tach signal wire since I have the early cluster and already have a separate wire ran for the tach. Can I connect the blue to the + on the coil? I think that's how it was setup to begin with. The car the harness came from is a euro spec 1991 245 with B230F, no options other than power steering and central locking which I think was standard in 1991.
 
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