As specified by the moderators of this forum, I searched for solutions to my problem but didn't find any help. So now I'm posting this in hopes of getting some information. I'm working on a 1990 240DL. There is no power at fuse #4 which is supposed to be a switched power source for the fuel pump relay. I have checked for power at the relay and found it on the heavy red wire. when I touched my test light to the black/yellow wire I hear the relay close and it lights the test light. None of the other wires have power weather the key is on or off. Yesterday I jumpered from fuse #5 to #4 and the car tried to start but wouldn't stay running. I've got 2 Volvo relays and 1 aftermarket. this car has been having electrical issues since the first time i worked on it such as the headlights going out during left hand turns. no reverse lights, and now this. I've changed both ECU'sand replaced fuel pump. PLEASE HELP IF YOU CAN!!!!. Thanks in advance.

 

As far as the headlamps go (off on l/h turns), sounds like an entirewiring harness issue.

 

Sounds like a bad fuel pump relay. The juice from the battery goes through fuse #6 to the fuel pump relay (red wire). When the relay is energized the juice goes to fuse #4 and to the main fuel pump.

 

This is definitely a bad relay. But the lights could be a couple of things. I assume when you say the head light goes out on left turns, you mean when it alternates with the turn signal illumination? That can be caused by a faulty ground wire and/or insufficient wire gauge in the harness. Onto the reverse lights, the reverse lights are connected to both taillights via the left taillight assembly. Open your trunk, and pop off the left (driver side) cover to reveal your taillight assembly. From a wire harness, an adapter with several connectors is attached to that assembly. The adapter simply holds the terminal ends of the wires and fixes them to the assembly circuit. I used to know exactly which color wire corresponded to which light, but it's been a while since I've looked at mine. The reverse lights are the two wires closest to the driver's side. I believe those wires are black (I may be wrong). Because of their location on the adapter and the fact that the harness is reasonably taught, the side of the adapter with the reverse light wire connectors tend to get pulled from its position. This either means the adapter is not completely attached to the assembly, or the terminal connectors inside the adapter have been disconnected.

 

Normal 0 On my 240s the wiring harness ground for the taillights is on the passenger side (right). There should be two grounds under that screw,one for the harness and one for the tail light assembly. The left side just grounds to the frame. Also look at the cabin light in the emergency brake cover housing on the floor between the front seats. The plastic breaks and the floor light for the back seats rolls around inside and grounds out the circuit which is on the same fuse as the instrument panel lights and one of the taillights.

 

Almost all of the wiring for the taillights begin on the driver's side, via a harness/adapter that is connected to the assembly's circuit board. Though each side appears identical, the passenger side does not contain as much source wiring as the driver's side taillight assembly does. Most of the connections on the passenger side are fed from the driver's side. Also, keep in mind that the sedan and wagon are slightly different (if you have a wagon, let me know). I finally found my old schematic, so this will explain the layout of a Volvo 240 series taillight assembly (I was incorrect about the exact location of the reverse light connectors on the adapter on my last post).

Adapter connectors on the driver's side (Sedan):
Black wire (Ground - stationary to frame via screw)
White wire (Fog light)
White wire (To right taillight assembly: fog light)
Green wire (Left turn signal)
Red wire (Running light)
Yellow/Gray wire (Brake light)
Black wire (Reverse light)
Black wire (To right taillight assembly: reverse light)

Adapter connectors on the passenger's side (Sedan):
Black wire (Reverse light - From left taillight assembly)
Yellow wire (Brake light - From left taillight assembly)
Brown wire (Running light - From left taillight assembly)
Blue wire (Right turn signal)
White wire (Fog light - From left taillight assembly)
Black wire (Ground - stationary to frame via screw)


The reverse light, obviously, is triggered only by a switch. This switch is linked to Fuse #5 in this order:

Fuse #5 > Blue wire > Reverse light switch > left taillight assembly > right taillight assembly.

You mentioned your involvement with fuse #5. Make sure that the fuse is working and properly connected. Most likely, you will find (if both reverse lights are not working) that there is a faulty connection somewhere in the adapter on the driver's side taillight assembly. The connectors are extremely fragile, and may fall out of place.

 

It sounds like you have replaced the ECU's and fuel pump relays. Check for spark - the fuelECU will not energize the pump relay unless it sees ignition pulses (as a safety feature).

 

Jlr, Of course you’re right I should have said my harnesses terminate on the right with the TAG and tail light grounds.

I’ve never mastered getting these worn tail light clips to work reliability, (and it seems to come up often on the posts). My quick and easy work around is an off the shelf 7-pin plug adapter. I soldered the male leads to the PC board and bugged the female into the harness. The process is easily reversible and anyone can still change the lamps according to the owner’s manual.

I say quick and easy but I’m an electronics engineer and have been soldering adapters for thirty years, so I THINK it should be quick and easy for most, using a very light touch and a low wattage iron on the bare copper film just below where the clip goes. Too hot and too long andyou will damage the PC beyond all repair.

 

Interesting. Knowing how sensitive the fuses and the circuits are, I would assume that soldering those connections would mess with the resistance. But if the connection in the assembly is successful, the other lights work, and the fuses are okay, then it just leaves a bad switch near the gear shift or a broken/corroded wire somewhere in the harness (which is likely, since the rear light wiring is unusually taught in the 240 series)