1980 Volvo 240 electrical wiring question ("box" on firewall)

It's a connector. Joins the wiring of the main harness in the car (dashboard, etc.) to the wiring on the engine. The wires there include starter solenoid power, temperature gauge sender, oil pressure warning light sender and power from the fuel pump relay under the dash to the EFI components on the engine (cold start enrichment, etc.).

Basically, the engine bay heat has cooked the wiring.

I'm sure that others will be able to provide information on repairing this using OEM parts. I repaired it on my '80 264 by replacing the entire connector with a GM part (soldered wires on car side of connector) then made a new harness for the 350 chev.

Also, I am having trouble starting this VOLVO and I'm wondering whether the cause might be electrical, perhaps related to said connector box/main harness. The engine runs fine once it's is on, but it's very hard to start -- needs a LOT of cranking, especially when the engine is cold (it's a little easier when the engine is hot). Could an electrical problem related to the connector box/main harness have anything to do with this.

Thanks. rnott at alexanria. ucsb. edu

athol wrote:

You have to fix the wiring harness anyway, why not fix it and see if the problem goes away? Also look for the same problem under the intake manifold and behind the alternator.

The black wire in the plug goes to the Oil Pressure Switch, the Red Wire goes to the Alternator D+/61 Terminal. After that I forgwt the colors. One wire goes directly to the starter solenoid (B-Y I think). One wire goes to the thermal timer--it's in series with the cold start valve. It allows the cold start valve to inject if the temperature is below 40 degrees and the starter is turning. So I guess one side of the thermal timer is B-Y and the other is white. The Cold start would be white on one side and black on the other (grounds on the manifold). The remaiing wire goes to the Auxilliary air valve and the control pressure regulator. Both have bimetallic strips that are heated by by switched B+ from the ignition switch--I think the blue wire. The air valve closes with time and current as does the CPR. Both devices ground under the same screw on the cold start valve.

To diagnose the hard start you need at least a test light to make some intelligent guesses. When the motor is spinning and not firing, connect the test light between the coil negative terminal and ground. If the light flashes then you have spark to the plugs. Pull a plug and see if it dry or wet. If it's dry then you are not getting fuel.

Typically long cranking times are due to a loss of rest presure. This can occur if the fuel pressure accumulator (can next to the main fuel pump) is leaking or the line pressure regulator o-ring in the fuel distributor is leaking, or the in tank fuel pump is not working or the fuel pressure check valve in the main fuel pump is leaking (more noticeable on hot starts) or there an problem at the air flow pressure sensor switch (engine vacuum lifts the air flow sensor plate, opens the switch and allows the fuel pump to run). If you disconnect the plug at the switch the fuel pumps will run whenever the key is in the run position. Another common problem is that the Control Pressure regulator has failed and the control pressure is high. This causes the engine to be lean although typical symtoms would be a start and stall on intial start up attempts until the cold start valve stopped firing (usually three or four attempts) then long crank times and noticeable loss of power or low power when started. Much like the symptoms of a leaking fuel accumulator.

If the plug is wet then you are not getting spark. Typical spark failures are: failure of the distributor pick up coil to send pulses to the ignition control unit (Often temperature sensitive) or the two wire lead from the distributor to the two pin connector going to the ignition control unit). Faulty distributor rotor, bad coil, bad ballast resistor, or bad ignition coil.

Hope this helps.

Bob

The wiring in '80s 240s was termed as "biodegradable" by Volvo aficianados. You can purchase a replacement harness, but it's a little expensive. You can get used ones from someone on the brickboard.com Volvo website. I think you have to remove the intake manifold to gain access to the wiring.

If you're not having electrical problems, you may be able to get by with wrapping the exposed wires with electrical tape, but wiring elsewhere in the engine compartment is probably going to cause problems later.

The cold-start problem is likely not electrical. There is a cold-start air valve bolted to the valve cover bolt on top of and in the middle of the engine between the head and the intake plenum. It has an elecrical connector and two rubber vacuum hoses connected to it. If this is not opening when cold, the car won't want to idle when cold and may die. Or it could be a cold-start injector that is supposed to richen the mixture during cold starts.'

All kinds of info can be found on the brickboard if you're willing to search for it. Good luck! KennyH

Horsepower is cheaper than therapy.

aficianados.

You don't *have* to, but it's less than a dozen bolts and makes life a lot easier so you may as well. Only downside is that you should replace the manifold gasket, though it does give you a nice excuse to do a really good cleaning of the throttle body.