swiftjustice44
Central Coast Brickyard
- Joined
- Feb 12, 2007
- Location
- DALLAS
We've all heard about the insulation issues with the late 70's and early 80's Volvos. Some of us have experienced it, some have seen it and, for many...it is enough of an issue to pass on what would otherwise be a great car. Volvo never admitted there was ever an issue, but they amazingly, came out with new engine harnesses with different part numbers that had new, improved insulation. Unfortunately, they never provided tower harnesses or "brain" harnesses to match. If you got to the JY to find another of these strut tower or through the firewall to ecu harnesses they are likely to be as bad or worse than the one in your car. There really is no option other than build an entirely new harness or patch the one you have. Building a harness from scratch is a royal PITA, but patching one is really pretty straight forward.
I bought a 1984 760T about 3 years ago and just recently sold it. The car is sitting at our shop until the buyer makes the final payment. The IAC has always been an issue with the car. I put a new one in shortly after buying the car without any improvement. The 84 760T use LH2.1 injection. It is essentially part 2.0 and somewhat 2.2 in appearance. It uses a specific ecu and when I opened it up, it smelled burnt. Squinting at schematics showed the IAC circuit was toast. Went ahead and converted the fueling to LH2.2 by re-pinning the AMM plug, and using a 007 AMM and a 541 ecu. Idled fine cold for awhile and then went back to its old tricks. I gave up and clamped the air intake hose almost closed. This effectively stopped the high idle when warm but made the car a little hard to start cold. Not bad here in Texas...but wasn't right, either. Not to mention the buyer wanted to know if he got to keep the hose pliers under the hood! Since I had concluded the issue was probably at the firewall, I promised him I would re-do the wiring there.
My first move was to recover the refrigerant and remove the accumulator/dryer. The firewall grommet is directly below and outboard of the dryer...getting it out of the way greatly improved access. I then disconnected the battery to prevent unexpected surprises! The engine harness had been replaced right before I bought the car and was in good shape. The eight pin multi-connector on the fire wall side was always VERY suspicious. Some one had wrapped each of the 8 wires with electrical tape, wrapped it all together and then smeared red silicone on the junction with the other 2 portions of the brain harness. I felt reasonably certain unwrapping the tape would bring to light why my IAC was not working. I really wasn't prepared for what I found but not really surprised, either. The previous owner was not mechanically inclined (his other car was a Catera!) and had paid a "professional" to do the job. This is what I found under the tape and silicone.
To get even better access to the wires, I pulled the glove box and disconnected the ecu plug. I then pulled the firewall grommet and extra wire, now freed, through and up into the engine compartment where I could reach healthy insulation previously inside the car. I chose to solder and use heat shrink tubing; some people use crimp connectors but I really prefer soldering when it involves anything that involves engine operation. It's permanent and water tight. Unlike crimped connections, soldered joints don't easily pull apart or vibrate loose. I'm fortunate in that I have pieces of harnesses from 3 different Volvos. I was able to get lengths of wire with the same color coding which made things neater.
Basically, what I did was go down each wire until I got to healthy insulation; using your thumbnail will find it rather quickly! In my case, the wire that was even just a few inches inside the fire wall was fine...outside the firewall there was almost no insulation. Then, I went to the spare harness pieces I have and found the appropriate color. Occasionally they had the correct female bullet connector but mostly not. I reused the non-disintegrated bullet connectors and soldered them on to a decent length of wire, fit the connector into the multi-connector and then eye balled the length back to where I was going to splice into the firewall harness wire. From that point, it's just a matter of removing insulation (the following photos shows one of the 8 wires, in this case the green one in the center of the first picture)
Twist the ends together...
Solder...
and, heat shrink...
And, repeat...and repeat...and repeat.....
I found that one of the 2 heater wires going to my O2 was almost completely naked of insulation while hidden inside the factory harness cover. So, I'm nowhere close to being finished.
Some pointers for soldering automotive wiring: Unlike perfect soldering as done on pc's and other delicate electronics...DON'T heat the wires until the solder flows onto them. If you do, the insulation will melt long before the solder flows. Also, your handy piece of heat shrink tubing that you slid onto the wire may very well start "shrinking" before you're ready! I've found the best solution is to pre-heat the gun until the tip smokes and will melt solder. Place the tip onto the joint and simultaneously feed solder to the side of the tip of the gun. It will run down onto the joint and hopefully stop. Flip the splice over to make sure the two pieces are joined. Let the joint cool and then slide the heat shrink over it and use a lighter, torch or heat gun to sel it up. If you have a random stray wire sticking up, coated in solder...take a pair of pliers and gently bend it over. These can either immediately poke through the heat shrink or later on after everything is buttoned up! To the extent possible, try to stagger where you make your splices; if all done in the same area the final product will be significantly larger in diameter than was the case originally, making the job of pulling it all back through the firewall more difficult if not impossible.
The firewall multi-connector is the Achilles heel; all the wiring is crucial AND very close to the turbo and down pipe. If you can do this job the other occasional areas such as headlights, fuel injector harness, etc. are a cake walk by comparison! Good luck!!
I bought a 1984 760T about 3 years ago and just recently sold it. The car is sitting at our shop until the buyer makes the final payment. The IAC has always been an issue with the car. I put a new one in shortly after buying the car without any improvement. The 84 760T use LH2.1 injection. It is essentially part 2.0 and somewhat 2.2 in appearance. It uses a specific ecu and when I opened it up, it smelled burnt. Squinting at schematics showed the IAC circuit was toast. Went ahead and converted the fueling to LH2.2 by re-pinning the AMM plug, and using a 007 AMM and a 541 ecu. Idled fine cold for awhile and then went back to its old tricks. I gave up and clamped the air intake hose almost closed. This effectively stopped the high idle when warm but made the car a little hard to start cold. Not bad here in Texas...but wasn't right, either. Not to mention the buyer wanted to know if he got to keep the hose pliers under the hood! Since I had concluded the issue was probably at the firewall, I promised him I would re-do the wiring there.
My first move was to recover the refrigerant and remove the accumulator/dryer. The firewall grommet is directly below and outboard of the dryer...getting it out of the way greatly improved access. I then disconnected the battery to prevent unexpected surprises! The engine harness had been replaced right before I bought the car and was in good shape. The eight pin multi-connector on the fire wall side was always VERY suspicious. Some one had wrapped each of the 8 wires with electrical tape, wrapped it all together and then smeared red silicone on the junction with the other 2 portions of the brain harness. I felt reasonably certain unwrapping the tape would bring to light why my IAC was not working. I really wasn't prepared for what I found but not really surprised, either. The previous owner was not mechanically inclined (his other car was a Catera!) and had paid a "professional" to do the job. This is what I found under the tape and silicone.
To get even better access to the wires, I pulled the glove box and disconnected the ecu plug. I then pulled the firewall grommet and extra wire, now freed, through and up into the engine compartment where I could reach healthy insulation previously inside the car. I chose to solder and use heat shrink tubing; some people use crimp connectors but I really prefer soldering when it involves anything that involves engine operation. It's permanent and water tight. Unlike crimped connections, soldered joints don't easily pull apart or vibrate loose. I'm fortunate in that I have pieces of harnesses from 3 different Volvos. I was able to get lengths of wire with the same color coding which made things neater.
Basically, what I did was go down each wire until I got to healthy insulation; using your thumbnail will find it rather quickly! In my case, the wire that was even just a few inches inside the fire wall was fine...outside the firewall there was almost no insulation. Then, I went to the spare harness pieces I have and found the appropriate color. Occasionally they had the correct female bullet connector but mostly not. I reused the non-disintegrated bullet connectors and soldered them on to a decent length of wire, fit the connector into the multi-connector and then eye balled the length back to where I was going to splice into the firewall harness wire. From that point, it's just a matter of removing insulation (the following photos shows one of the 8 wires, in this case the green one in the center of the first picture)
Twist the ends together...
Solder...
and, heat shrink...
And, repeat...and repeat...and repeat.....
I found that one of the 2 heater wires going to my O2 was almost completely naked of insulation while hidden inside the factory harness cover. So, I'm nowhere close to being finished.
Some pointers for soldering automotive wiring: Unlike perfect soldering as done on pc's and other delicate electronics...DON'T heat the wires until the solder flows onto them. If you do, the insulation will melt long before the solder flows. Also, your handy piece of heat shrink tubing that you slid onto the wire may very well start "shrinking" before you're ready! I've found the best solution is to pre-heat the gun until the tip smokes and will melt solder. Place the tip onto the joint and simultaneously feed solder to the side of the tip of the gun. It will run down onto the joint and hopefully stop. Flip the splice over to make sure the two pieces are joined. Let the joint cool and then slide the heat shrink over it and use a lighter, torch or heat gun to sel it up. If you have a random stray wire sticking up, coated in solder...take a pair of pliers and gently bend it over. These can either immediately poke through the heat shrink or later on after everything is buttoned up! To the extent possible, try to stagger where you make your splices; if all done in the same area the final product will be significantly larger in diameter than was the case originally, making the job of pulling it all back through the firewall more difficult if not impossible.
The firewall multi-connector is the Achilles heel; all the wiring is crucial AND very close to the turbo and down pipe. If you can do this job the other occasional areas such as headlights, fuel injector harness, etc. are a cake walk by comparison! Good luck!!
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Aaron, as Andysbeta has pointed out, patching on the engine harness itself is a band aid fix at best. If you can find the updated harness, swap it out. Check fellow TB'r Dave Barton's web site for the updated number for your Brick. davebarton.com
