20 Most Recent 1990 Volvo 740 - Page 4 Questions & Answers

Sorry, I just notice the year & model. If all the lights are working, you could have a bad ground connection or the bulb integrity relay is defective. You will have to get the wiring checked with a test light or volt meter to see where the problem is.

If it looks like a light bulb with an X over it, it means you have a bulb headlight or a tail light burned out.

I'm having this same exact issue, but i checked the OBD system and there were no fault codes. please post something back if you figure out what it is. or email [email protected]

if its the rear mounted distributor to the cam by firewall,looking inside cap it's the bottom contact. you can verify is point to point contact with an ohm meter.the firing order once the cap is reinstalled looking left to 4312.which translates to 1342.BE CAREFUL OF THE 3 PIN PLUG ON SIDE OF DISTRIBUTOR & wiring becomes brittle.

The wiper motor is underneath the metal bonnet in between the wiper arms (the piece that looks like an air scoop) the comes out hard through prying and sometimes there are 4 screws that hold it in. Inside the engine bay. When prying the bonnet off start from the drivers side top and work your way across the top. Then once that is off then it is only 2 10 or 12 mm bolts. and a plug and that's it.

• You have two fuel pumps. A main fuel pump and an in tank fuel pump and one fuel injection/pump relay that turns the fuel on for the both of them at the same time and each fuel pump has a dedicated fuse.
• So your vehicle has 1- relay, 2 pumps, 2 fuel pump fuses [1 for each pump ]
• The relay and both fuses are located under the drivers side of the dash in a little fuse/relay panel.

• Hope this helps and thank you for using FixYa

Regards, Tony

Hi,
That sounds like an ECU problem.
Better bring that Volvo to the nearest dealer and have them scan your computer for any anomalies in the system.
Hope FixYa solved that problem.

You don't really need a diagram, it's simple. If you open both tail light boxes in the trunk you will see at the connector on the bottom a yellow wire in the first position. That goes to the brake bulb. If both tail lights do not work, make sure you are getting power to the driver side light first, if it is not getting power, the passenger side will not work either, they are in line with each other. If it is only the passenger side not working, the bridging wire could be bad.. try jumping it. Also, make sure you are getting power inside the tail light bulb holder. The metal connections can come loose. If there is no power to the driver side tail light it could be the bulb failure relay, that is the round red relay in the rear left side of the fuse box behind the ash tray/ cigarette lighter below the radio in front of the shifter. You should be getting power to the third brake light in the rear window...that is a different circuit and will not be affected. Try changing out the bulb failure relay, it supplies the power to the tail lights.

Blown fuses. Find the proper fuse and replace, all should be well.

The idle speed is controlled by an Engine Control Module (ECM).
It needs to be put on a computor to be checked.
The idle air valve provides the control for constant idle speed. In order to set the correct air valve opening to achieve constant idle speed, the fuel injection control unit uses information from the air mass meter, A/C switch, throttle valve switch and the ignition control unit (RPM signal) to regulate the output current to idle air valve. This means, there is alot of things that can make the idle speed go up or down...Hope this was some help to you??

Check the next diagram (click image for zoom)...



Fig. 1990-95 Volvo 740,760,780,940,940SE,960 Chassis Schematic

Hope this helps.

Either you have a problem with the TCS (Traction Control System), or the TCS is switched off. Most cars with TCS have a button on the shift or the dash labeled "TCS" or "TCS OFF". Find the button, and press it with the car running in gear. If the light goes out, problem solved.
If you cannot manually disengage TCS (no button), or when you press the TCS button the light flashes, check all your brakes and make sure none are dragging or worn out. Also make sure all your tires are properly inflated and balanced, and none are worn out.
TCS works by controlling your brakes on slippery roads and will dynamically apply the brakes to each wheel in order to prevent a skid, even when your foot is not on the brake pedal. During normal driving, the TCS light is out and will either come on briefly or flash when it is active and preventing your car from going into a skid. When the light is on constantly, the system is disabled- either because it was shut off by the driver pressing the TCS (or TCS OFF) button, or because the system has detected a brake problem and automatically disabled it for safety reasons. Worn or dragging brakes, a tire that is flat or worn, or even a wheel that is badly out of balance will cause the system to disable itself, and a severe wheel alignment problem will also.

Look at the socket? Are there two contacts? If so, 7528 (or 1157, same thing) is correct (and that's what the parts catalog will show). However, in the case of my 1991 740, there is only one contact in each socket. If that is the case use an 1156 bulb.
I spoke with an expert Volvo mechanic and he told be Volvo used two different tailight assemblies, a Hella and another one I can't recall by name. He said there appears to be no rhyme or reason as to what car has what, and this is the reason for the discrepancy in the proper bulb. The only way to know for sure what you have is a visual inspection on the unit.

sounds like you may be experiencing a bad fuel pump that is able to supply for a short time then gives out but to be sure check your filter first if you can blow through it easily your pump may be suspect and require further testing to verify such as a fuel pressure test while running and such

check the ground on the intake, for bad connection.

Your brake light switch is just above your brake pedal, under dash/steering column. It's small plastic unit with 2 wires coming from it.

Pull the top off the distributor cap and see if there is moisture under there. WD 40 is good for driving out the moisture. The WD stands for "Water Displacer"

I've run into this problem on different makes and models, But I haven't done a volvo yet.This works to variing degrees, some would run better and some it was like installing a new engine. Anyway what I do is to clean the throttle body, you'll need a small brush( toohbrush) and a can of brake clean. remove the air plenum and clean inside the throttle, open the throttle plate and use the brush to clean as much as you can. Don't be afraid to use the brake clean. After you,ve cleaned start the engine, this may take a minute. rev the engine up and spray some of the cleaner in the throttle. Also check your air filter, if it's dirty replace it.

This sounds a lot like a knackered air valve. This valve regulates the idle speed. When it fails open, too much air gets in, forcing the system to richen the mixture ratio. When it fails closed, not enough air gets in causing you to make up the difference by stepping on the gas pedal. Depending on fuel system type (Bosch or Regina) it could also be a failing air mass meter (Bosch only) or a faulty MAP sensor (regina).

I see you changed the air valve, but did you check the connector for cleanliness? A low voltage on the connector makes it do weird things.

If the replacement air valve is known good, then that leaves the air mass meter (Bosch) or the MAP sensor (Regina). The 0xygen sensor is a PTC on the Regina system - so if you changed it make sure you got the correct type. Most Oxygen sensors are like galvanic batteries, not resistors, but on Regina fuel systems the latter type applies. It is just a resistor.

If you have a Regina fuel system (square ignitor on the driver's side) the MAP sensor will fail like this. Ensure the vacuum line is connected to it and the connectors are clean. If the system can't find the MAP sensor values, it guesses and you get a rich mixture by default.

If you made it this far, check out your ignition system - the crank angle sensor sometimes gets flaky and the ignition system starts to guess as to where Cylinder 1 is - and retards the timing, sometimes shutting off power to the ignition coil completely if it gives up.

Taking this one step further, the fuel pressure regulator could be bad - resulting in too high fuel pressure causing a rich mixture ratio.

Read the codes from the fuel and ignition system. This involves opening the Lego like cover to the diagnostic jack, driver's side. Position 2 is for the fuel system and position 6 is for the ignition system. You plug the test plug into each port respectively and press the button for at least one but not more than three seconds. Any blinking code other than 1-1-1 is a fault code. The system flashes the codes by blinking the LED, pausing, blinking it again, pausing, blinking one more time. For example, I have code 232 (Incorrect mixture ratio - 02 sensor at backstop) it would blink twice, pause, three times, pause, twice, pause and stop.

Always read the codes with the engine off and key in the ON position.

Good luck - take your time and don't waste money on mechanics' work you can do yourself. Not to knock any mechanics out there (I have been doing this work for 17 years!!) but some will take your money - best method to empowerment - DIY.

-AS

Change the fuel filter, and ensure the pump(s) are working. Some cars only have one pump in the tank. Others have two, and they are both driven from a relay in the engine compartment. Depending on model and year, this relay may be near the anti-boil overflow bottle, or on the driver's side, near the battery. If you turn the key to ON you should hear a gentle whir for two seconds. If that sound isn't present, the pump or relay is suspect. If it is loud, the pump is failing.
When fuel pumps fail on these cars the car typically will not run when the tank is less than half full. In the case of turbo models, the main pump under the driver's side has to pick up the extra slack. In my experience, it is better to change both pumps when one pump has failed. When the tank pump is noisy, it is failing.
Of course, check the fuses before condemning the pumps. -AS