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

My question is about this electic box, mounted on the firewall to the
left of the engine, see image here:

http://www.alexandria.ucsb.edu/~rnott/tmp/Volvo240_electricDetail.JPG

The bigger overview picture is here:
http://www.alexandria.ucsb.edu/~rnott/tmp/Volvo240_electric.JPG

Can someone tell me what this box with six connections does? Two of
the wires are very frayed, as you can see (the one on the third row to
the right, and the lowermost one; what are those?).

I'll be grateful for any information on this (description, web links,
books, anything).

Thanks,

Wolfgang
Santa Barbara, CA

 

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

 

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.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

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.

 

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.