Looking for any pic of the injector ballast resistor pack on a 1989 740 GL?

[JohnnyU9999]

Hi y'all!

Does anyone have a picture of where the injector ballast resistor pack is located on a 1989 740 GL?
I have spent several hours and cannot find it! According to various posts, its the likely culprit but I can't test it if I can't find it.

Looking for any pic of the injector ballast resistor pack on a 1989 740 GL..

Thanks!
Your fellow Volvo enthusiast,
John U

[volvolugnut]

In some cases the design of the 740 is the same as the 240. I have a very detailed Bentley Publishers manual for Volvo 240s. I can find no reference to a fuel injector resister.
Do you perhaps mean the main injection fuse located on the drivers side fender in front of the shock tower?
volvolugnut

[Rockyrider]

On my 1989 740T wagon it is located inside the engine compartment on the drivers side fender close to the front of the car very close to the battery. In fact, I discovered this a few years ago when I removed and replaced the battery, and afterwards it ran terribly, very rough idle, engine shaking, and it hesitated when pressing the gas pedal. Sounded awful through the exhaust also, like a burnt cylinder valve. Turned out that I pulled on one of the ballast wires when removing the battery it wasn't making contact. I removed the unit and resoldered the connection, problem solved, then it ran normally. Recently (several years later), it started running very rough again in the same way, and I first thought it was a burnt exhaust valve, but then checked the ballast resistor, and one of the other wires had come loose, it was still attached, being held by the heat shrink wire covering, but had corroded underneath and wasn't making contact. I had not removed the battery or put any stress on the wires this time. Again, I resoldered this connection, checked the others, and it's running fine again. Apparently, the connections are subject to corrosion (they're not soldered originally, crimped or spot welded I think), and can break just by corrosion. To diagnose, try pushing in each wire onto each resistor to see if the engine runs any better. There are 4 resistors in the cluster, with a 5th connection in the center which attaches to the other side of each resistor. To test with an ohmmeter, disconnect the plastic connector and connect the meter leads to the center wire and each resistor. Each resistor should measure 6.5 kilo ohms. The wires up to the connector look like speaker wires (clear insulation), and look like some kind of homemade repair, but that is original. The car will run terribly if one resistor is disconnected, and it won't run at all if the entire ballast resistor is disconnected. You can use vinegar to clean the corrosion, and it's a good idea to get some solder liquid flux so the solder sticks. I also use some heat shrink insulator tubing to cover the connection, that's the best, but you can also use electrical tape. Good luck!

[Rockyrider]

Ok, after my last post, I checked the Volvo Service Manual Wiring Diagrams for 1989 740's. It shows all of the possible engines for a 1989 740, which include 4 non-turbo and 1 turbo engine. It looks like the only the Turbo model has the fuel injection ballast resistor. This is engine B230FT with LH-Jetronic 2.2. All of the other wiring diagrams for other motors/fuel injection systems do not have an FI ballast resistor. This includes the B230F engine with LH Jetronic 2.4, which is most likely the engine you have. A tell-tale is that the turbo engine does not have a Cold Start Valve, and all of the other engines shown in this wiring diagram book do have Cold Start Valves. So, if your car has a Cold Start Valve, it most likely does not have a FI ballast resistor, which would explain why you can't find it.