Q: How difficult is installing a wire harness?  Will I need to pay a mechanic to install it?
A: This job has a higher degree of difficulty than most home-mechanic tasks, however it can be done in an afternoon with ordinary automotive tools.  It is more difficult on some models than others.  On early 4 cylinder 240's (up to '82, and all Turbos), I usually remove the intake manifold to better access the connections underneath.  These mechanically injected 240's (non-turbos) and the 240 Turbos seem to be the most difficult as far as reaching connections and those intake manifolds are always in the way. But all of them get easier with the intake manifold at least partially pulled away from the engine.  On the other hand, most later 240's (1983 and later non-turbos) and 700 series cars will have much more room to reach under the intake manifold and I generally do not remove the manifold when changing a 4-cylinder harness on those cars.

Aside from the possibility of removing the intake manifold, the most difficult part of this operation is getting the connections right the first time.  It can be very intimidating to a first timer.  This is why I always recommend that when disassembling multiple parts in an engine bay, you keep good notes on each connection and vacuum line that is unplugged.  Label the connections before pulling them apart.  Maybe use a colored paint pen on the connectors or make a label out of tape.  Make your own drawings too.  A digital camera comes in hady here.  It makes life so much easier when things are being reassembled to be certain of how they go. 

Further, each wire inside a harness is color coded, so it is a good idea when removing an old harness to pull back the rubber insulating boots on the connectors and write down the wire colors you see in conjunction to where they plugged into.  This way you will be able to check the wire colors of the new harness the same way and verify that the correct connections are being made.  Just a little extra peace of mind.

A very common email I receive after someone experiences a no-start after a harness installation is that the starter won't turn when the key is turned to 'start'.  This occurs when the starter engagement wire (usually a blue/yellow or blue/green wire) that plugs into the spade on the starter solenoid is plugged on the wrong spade.  The correct spade is usually the lower one or the closest one to the driver's fender, tepending on how the solenoid is mounted.

Regarding the use of a professional mechanic... many people do pay their mechanic to install a harness.  It has been my experience that a mechanic will charge about 3 to 6 hours labor for this job.  Check with your mechanic beforehand.  Some people have found mechanics who refuse to install used parts or any parts brought in by customers.
           Some helpful instructions are linked below... Click here.

If you decide to install a harness yourself, here are some other suggestions or considerations for maintenance items that can be done at the same time (some models are difficult unless you remove your intake manifold).
--    If you remove the intake manifold always replace the gasket, preferably with an OEM Volvo or Elring brand gasket, since they seem to be softer and a higher quality than the hard paper gaskets I have seen.  An Elring brand gasket will be fine if a Volvo gasket isn't available.
--    Clean your throttle body and replace the throttle body gasket if removed.
--    You might consider replacing some Engine Temp Sensors. IPD (www.ipdusa.com) has a selection.  (Image at right from IPD catalog) > > > >
--    Replace all small rubber vacuum lines if they're old.  They get hard and stiff and cracked and will cause you problems eventually.
--    Change the two heater hoses coming out of the firewall.  I have seen MANY fail after about 8 or 10 years.
--    Remove and clean (or replace) the oil breather box under the manifold.  The oil breather box is about $35 new from Volvo.

Q: Some people are advising me to repair my old flaking harness.  They say that buying a new one (or used one) is a big waste of money.  What do you think?
A: I am not a fan of patching a flaking engine harness or rebuilding one, unless that is your only choice (if a new or used one is not available).  I have followed many posts on the internet on this subject, some advocating a new harness, and some advocating the repair of the old one.  I have personally observed the extent of degradation a defective harness is subjected to and it is my belief patching an old harness that is disintegrating is a short-lived solution in most cases.  And please remember the wire insulation is not the only problem with a 20 plus year old crumbling harness.  The soft silicone female bullet connectors and the plastic plug (socket housing) connectors will often crumble away too.  Some people I know have been successful in building harnesses from scratch using salvaged parts from wrecking yards (and I have done this for some extinct harnesses too).  This CAN work just fine as long as the builder fully understands the harness circuits.  But such a task is very time-consuming.

I have seen posts advocating partial repairs of old harnesses... such as the replacing of only the exposed wires.  While some wires may seem less affected than others, unless you actually check every inch of every wire, you're taking a pretty good risk.  Some will tell you that the wires inside the black vinyl covering will be just fine because they were protected from the elements.  Again, this is NOT TRUE at all!.  The killer of these original 1980-'87 harnesses is not the elements. It's ENGINE HEAT (not the weather and not even oil or fuel).  This is why you will usually find that wires under your dash or farther from the engine are in perfect condition when the same wires closer to your engine are bare or flaking.  While it is true that the wires in a vinyl sheath might be protected from heat longer and could be in better condition, if that plastic sheath has been sitting near a hot engine for years, then the protection is minimal and short-lived.   I have opened many plastic covers of old harnesses that were near the engine only to find bundles of wires with no insulation left at all.

Q: Are the used harnesses you sell ORIGINAL VOLVO PARTS?
A: The used ones I offer are almost always original Volvo parts.  Unless stated otherwise, they are all Genuine Volvo, manufactured by Volvo (or by whoever makes them for Volvo), and they carry the correct Volvo part numbers.   On occasion, I offer used aftermarket harnesses, as some of the new harnesses offered in the past were from non-Volvo suppliers.  Aftermarket ones are still high in quality, but can usually be found for a lot less money than the high-priced genuine Volvo harnesses.  Aftermarket harnesses are clearly identified as such when I offer them.

NOTE: All later replacement harnesses are assigned different (newer) part numbers than the original harnesses they replaced.  For example, the original part number for the 1980 240 harness was 1259454.  Volvo then changed the number of it's later replacement harness to 3515395, and now the most current version is 9139228.  If you are still uncertain about a particular part number fitting your car, you may call your local Volvo dealer parts department to verify the number needed for your application, or feel free to send me a message and I'll be happy to help.

Q: What about the fuel injector connections on EFI models?  Do they need to be placed in a certain firing order?
A: No.  These connections all contain the same wire circuits and are interchangeable.  This is because the Volvo electronic fuel injectors fire all at once when running. This is known as "batch fire."  You will notice that the injector leads are different lengths.  The only thing you need to be concerned with is arranging these leads for the best fit so that each connector comfortably reaches an injector without being stretched or strained.

Q: I'm somewhat cautious about buying a USED electrical part.  What if it doesn't work?
A: Buying any used part has risks.  There is always the possibility of hidden damage.  For any used harness that I sell, I take a lot of time cleaning and carefully inspecting each one before offering it for sale.  I have sold over 500 of these harnesses over the past ten years and NEVER has one been defective.  Keep in mind that I back all used harnesses with a 100% satisfaction guarantee and if a customer has a problem with a used harness I will work diligently to either solve it or take back the harness and return a full refund.  This guarantee applies even if you don't like the appearance of the used harness (see Return Policy above for details).  I'm a Volvo enthusiast and it's your satisfaction I want.   I believe in keeping good customer relations and I have a lot of repeat customers as a result.

Q: How do I know that a new or used "later replacement harness" will not rot away after a few years like the original one did?  I understand it took several years before they began to fall apart.
A: Yes, in most cases it took several years for the original ones began deteriorating.  The Turbo cars had more heat under the hood and those went faster.   And cars that were in mild or cooler climate areas did much better than cars in hot desert regions.  I talked with a former Volvo technician from Phoenix, Arizona, who told me they had to replace harnesses in many of these cars by the time they were three years old. 

But the later replacement harnesses (which were all made after 1988) have proven themselves for many years now.  I have examined hundreds of older Volvos with these replacement harnesses, as well as hundreds of 1988 and newer Volvos, and the you rarely find deterioration in the later harnesses, even after being used for many years.  The visual difference between an original defective harness and a later one is easy to see.  If the later harnesses were going to fail, I would have seen evidence of it long ago.

Q: I have rotting wires at the plug near the firewall on my 240.  Since this is NOT part of the new replacement harness I'm replacing, where can I get new wires and connectors for this area?
A: Your Volvo dealer sells replacement bullet and socket connectors with wire "pig-tails" just for this purpose (see photo).  The wire color comes in white only (40 inches long).  The Volvo part number for the female socket piece is 3523813 (shown in photo to the right) and 1323247 for the male bullet pigtail...  price is around $5 each.  If you need the rectangular gray 8-pin harness connector housing (bullet or socket housing), it now comes in black only and is Volvo part number 967808 for the female socket housing and 967809 for the male bullet housing.  I think these are about $5.00 each from Volvo also.

Q:  When splices are made in a harness, do you recommend crimping or soldering?
A:  Many experts will recommend soldering because it provides a more solid connection with less chance for corrosion to occur and degrade the connection.  Soldering can be more important in wet climates or high-corrosion environments.  Soldering is more time-consuming and it still needs to be insulated (use heat shrink tubing if possible... tape if necessary).  Soldering has it's limits and can crack under stress, movement or vibration.

For my own car projects, most of the connections I make are crimped (as were all of Volvo's connections originally and all of the connections in their current harnesses).  So I see nothing wrong with crimping, as long as it's done with care.  If you are going to crimp using insulated butt-splices etc., please purchase a quality crimper like the one pictured and use the crimp area that has the protrusion for deep crimps.  Please do not rely on cheap stamped-steel crimpers like the ones you see for a few dollars in discount auto parts stores.  A quality crimper will cost you $20 and up and will last the rest of your life.

Q: What about the harness that goes to the ignition ECU or other parts of the ignition on a 240?  Is that part of the ENGINE wire harness?
A: No. While the engine harness does connect separately to the ignition harness in a 240, Volvo made the two harnesses separate.  If you need an ignition harness for a 240, it is a separate part.  The good news about 240 ignition harnesses is that the original ones last much longer than the engine harnesses did.  So there is a very good chance you will not need to change your ignition harness.

Before criticizing Volvo for making these harnesses separate and making life more complicated, consider that on many 240 models more than one type of ignition was offered.  For instance, the '83-'84 240 non-turbo Main Engine Harness didn't change during those two years, but more than one type of ignition appeared on these cars (Bosch and Chrysler MPG), therefore more than one type of ignition harness was required to make it work.

One of my customers, Dick Reiss, took the time to post the following directions on the Brickboard after completing his wire harness installation on his 1987 740 GLE (non-turbo).  He graciously gave me permission to publish it here.  (Note: '85 and '86 740 GLE replacement will be nearly identical. 700 Turbo car replacement will have some differences as some components are in different locations)

For those feeling threatened by this job, it can be done relatively easily, in my case under 4 hours of puttering slowly.

First, unhook the ground battery cable.
Remove the intake hose from the AMM to the throttle body (different for turbo cars).
Remove the idle speed motor (under intake manifold), sliding it out of its holder. Hoses too.
Remove the top portion of the flame trap and hoses (through top of intake manifold).
Under the intake manifold... unhook the inline wire connector to the AC compressor -- makes it easier to work in the area.
Jack up passenger side of car and remove the belly/splash pan.
Remove oil pressure sender wire -- a round push together type clip holds the connector to the oil pressure sender on the block.
Remove the two 10 mm nuts and clamps holding the oil pressure wire to the underside of the engine. Take clamps off the wire.
Label all the wires you remove and/or write them down noting colors ---DO IT!!! You can screw up!
Remove the two red wires (one fat cable and one small one) from rear of the alternator.
You might detach the blue ground wire from the alternator too as it will be easier to work in the area.
Remove the clamp behind alternator holding the wires to the intake manifold brace -- 10 mm hex bolt.
Remove the top 10 mm hex bolt holding the power steering resevoir to the fender and loosen the bottom one. Now lay it over toward the firewall. The harness is routed under it and this will allow it to be removed.
Trace the old harness from the engine to the fender and you will find another clamp on the driver's side fender that needs to be removed -- 8 mm hex bolt.
Unplug the large gray 8-wire connector and the AMM connector on the driver's side fender (this plug will only plug back in one way).

Lay out your new harness and get acquainted with it.  Label the connections.
Now start to remove the old harness beginning from the driver's side fender moving toward the engine and start to plug in new stuff. This is a real mess of wires and connectors, but your labels will help. Look carefully at the routing of the harness around the flame trap and dip stick. It will help if you route your new harness in a smiliar manner.

Under the Intake Manifold: Remove the knock sensor connector and temp sensor connector (gray).  The knock sensor cable is NOT replaced with a new one from the engine harness, it's just easier to work with it out of the way.

Remove the large red cable (13 mm hex nut) and female wire connector on the starter, remembering to write it down and label what goes where (there are two connections on the starter that the small female connector will fit on.... but only one is correct.  This is the most common "no-start" problem for installers).

You may need to snip a number of black nylon cable zip-ties along the way.

Unplug the coolant sensor connector (this is a 2-wire spring type connector) by the heater hose inlet on the head (under the intake manifold). Look for more zip-ties to clip.

Go along the firewall and try to unhook the heavy black zips-ties holding the old harness --- they will probably break since they're brittle.  Now you can remove most of the old harness from the engine area and install the new.

Passenger fender:  Remove the two large Phillips screws holding the coil in place and lay it toward the center of the engine bay.
Clip the zip-tie holding the two large gray plugs under the diagonal brace and remove the one wire from the coil that goes to the old engine harness (write down which side of the coil it plugged in to).
After removing more zip-ties you can remove the old harness completely and replace the new. Install new zip-ties where old ones were.  Don't get stingy on these as the harness needs to be held well. Recheck and reinstall things as they were.

This is a good time to service oil and flame trap area if needed.  The main thing is ensuring success is to make drawings, write things down and label harness connections, both old and new.

Dave Shannon's excellent Volvo page has a very good article on changing the engine harness in a 1981-85 240 Turbo and a 1983-84 240 (non-turbo).  Click this link to find it... http://www.homestead.com/volvo2/quickindex.html

And finally, here is an excellent article on Volvo chassis grounds and other good stuff that I thought was so good, I wanted to share it with you...
Volvo Electrical System Service: In Search of Good Grounds, Bob Kraft, ImportCar
http://www.babcox.com/editorial/ic/ic129744.htm
 
 

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