Volvo 940 Obd Codes

[Muredac Ford]

Volvostarted using self-diagnostics on its Bosch LH 2.4 engine management systems in 1988 on 700 series non-turbo cars and in Regina-equipped cars. Earlier Bosch LH 2.2 and Turbo cars until 1990 had very limited self-diagnostic capability using an LED tester. In LH 2.4 cars, If a system fault occurs, then the "check engine" lamp will illuminate, signifying the presence of a fault code. For every model year using LH2.4 up to and including the '95s (except 200 series DLs and GLs), you can flash out fault codes, as well as perform input and output testing, through the OBD-I diagnostic connector unit simply by inserting a little self-contained probe and pressing a button. You do not need a special scan tool to read codes. As electronic systems were added to more Volvo models, more socket options and even more diagnostic connectors were added.

Unfortunately, you cannot use a generic code reader on any of these OBD-I cars: you have to manually extract the codes from the systems as noted below. 1996+ cars have the entirely different OBD-II system which requires a computerized code scanner to read codes through a special data link.

The diagnostic connector units for OBD-I systems are small black rectangular boxes mounted in front of the left-side(driver-side in LHD countries) shock tower. Earlier cars have only one unit ("A"); later cars have two ("A" and "B"). Diagnostic connector "A" contains the test terminal probe (the wire mounted on the side of the box in the picture) used in both A and B along with the test button and the LED readout lamp. In diagnostic connector A, socket 1 is for the electronic transmission (if your 960 or 90-series car has the AW30/40), socket 2 for fuel injection or Motronic, socket 3 for ABS, socket 6 for ignition and socket 7 for the instrument cluster. If the 1992+ car is so equipped with connector B, socket 1 is for the climate control, socket 2 for cruise control, socket 5 for the SRS and socket 6 for the memory seats.

For later 1996+ OBD-II equipped cars, the diagnostic connector was changed to an electronic data link and moved from under the hood to in front of the shifter in the console. As a result, you need a computerized scan tool to do everything from checking for codes to resetting the maintenance light. Maintenance light resetting, by the way, was returned to a push-button method in the very late '90s.

Note that 200 series DLs and GLs have self-diagnostic capability only for fuel and ignition control. All other systems except 1990-93 SRS require a proprietary tool. For '90 to '93 models with air bags, just jump a terminal to ground to get codes out of the system.

[Response: Chris Herbst] I have run into a LOT of Volvo products with bad diagnostic readout units, usually caused by corrosion. While it is possible that there is no signal TO the diagnostic unit, it is just as likely that either the connection in the terminal, or the connection TO the unit from the ECU computer, is bad. You should try cleaning those connections, and if necessary you can jiggle the connections until you DO get proper readings. I've never had it where I wasn't able to at least read codes and reset the computer, although sometimes it was when I was squeezing the connections into the diagnostic readout unit, or jiggling them around. While your problem could be the ECU, more likely it is corrosion or a bad connection, especially if the engine is operable. [Chris Mullet] When I could not get the LED to illuminate, it turned out that the LED itself was burned out. I picked upanother one off a wrecked car and it got me back into business.

If you have an ohm meter to test continuity, you can pop the unit open and check out the LED, resistor, button contact, etc. Be careful as there are a couple tiny springs that can go flying when you open it up. [Doug Bennett] Remove the unit from the fender wall. The there is a plastic cover thatcovers the button. There are two small tabs, facing inward. Depressthese with a small screwdriver, and carefully swivel the plastic coveraway. The button will now come out. BE CAREFUL NOT TO LOSE/DROP THE TWOSMALL SPRINGS ON EACH LEG OF THE BUTTON! Luckily, I had a magnet handy.On both the bottom of the button and down in the test unit itself, are the contacts. Mine were filthy. 15 seconds with a Dremel, reassemble, and all is well!

Does the OBD Code Pinpoint All Problems? [Editor] Absolutely not: the earlier OBD-I systems are quite crude and provide a hint only. Coolant temperature and knock sensors, for example, can fail without any OBD codes being set and the only real test is further diagnostics.

The following section describes the onboard diagnostic codes for the Bosch LH2.4 and Regina fuel injection and EZK 116/Rex1 ignition systems used on later 1988+ 2XX, 7XX, and 9XX Volvo cars. If you have the Bosch LH2.2 or earlier systems, you do NOT have OBD capabilities and will have to diagnose sensor and performance problems using traditional manual techniques.

The later fuel injection and ignition systems incorporate a built-in diagnostic subsystem that is able to test various sensors and fuel injection or ignition components and report the results. This diagnostic system is located behind the driver's side strut tower in the engine compartment with a readout box with several functional modes. 940 cars have two boxes: "A" and "B"; the former is used for engine diagnostics and ABS; the latter for SRS and cruise control. If fault codes related to the emission system are registered, the "Check Engine" lamp on the instrument panel is lit. The test cable is mounted to the side of A.

To operate the diagnostic system, open the A box cover and insert the end of the test cable mounted on the side of the box into either socket 2 for LH 2.4/Motronic 1.8/Regina fuel injection diagnostics and component or sensor tests or socket 6 for EZK 116 ignition or California EGR diagnostics. Place the ignition key in the ignition lock and note where key position II "KPII" is on the switch. To operate the system:

View Fault Codes ListOnce upon a time, diagnosing a vehicle's issues took (what old-school mechanics call) "brute-force diagnostics." Back then, having a Volvo fault codes list would have sped up the overall repair time. Not to mention saving a few headaches. In the old days, you needed to have a firm understanding of the "big three" that kept a car running in order to source a problem, as well as a trained ear, nose, and set of eyes to spot potential symptoms. For the last 50 years, diagnostics have evolved with the advent of engine computers (otherwise known as ECUs, ECMs, or BeCMs, among others), and now, cars can self-diagnose engine and other problems thanks to a wide range of sensors. The vehicle relays this information to the mechanic via stored Volvo trouble codes, and the mechanic can spend more time fixing with precision as opposed to brute-force testing.

In short, understanding the entirety of the Volvo fault codes list is easier than you might think, but having some historical perspective can help. Scroll below to get a brief history on engine diagnostics and see how you can retrieve your stored Volvo fault codes list like the pros who carry out Volvo auto repair in Lexington every single day.

For well over 100 years, the ICE (internal combustion engine) converted stored energy into kinetic energy through the combination of fuel, air, and fire (yes, those are your big three). Most of us know that generating heat (converted energy) at a fireplace requires something to burn, proper airflow, and a spark. Without those big three components, cavemen would have frozen, and ICEs would not work. If a cave dweller in Lexington could figure out how to maintain a state of converted energy, rest assured, you can understand how an engine works!

There are mechanical systems responsible for sustaining the big three, and when one fails to operate, engine performance suffers. About 50 years ago, Volkswagen Group was the first to implement a computerized monitoring system to aid in diagnostics. This system was clunky and crude and copied by other manufacturers. Each manufacturer had its own system, its own codes, and its own procedures.

These proprietary systems were the first generation of onboard diagnostics (OBD-I). In the early '90s, federal and international law required that these trouble codes be easier to read by consumers and other parties, and OBD-II systems were born. Feel around in the driver's footwell of your car. There's a trapezoid plug somewhere down there. This plug accepts an innumerable number of specialty (and customer-friendly) scanners by which you can identify your diagnostic trouble codes (in this case, your Volvo DTC codes).

Engine codes, as you might think, are the most common and widespread because, if you recall, without the big three, there's no car or any other system that the ICE supports. These Volvo engine codes have alphanumeric designations, like P-3001, P-1238, and so forth. While the numbers themselves might seem meaningless, you can quickly pair them to a Volvo fault codes list, which will identify the faulty component or system, as well as test & repair procedures.

If your thinking cap is on, you might have guessed that there are specialized code sets specifically for each system: Fuel codes, Air codes, and "Fire" codes (ignition codes). There are literally thousands of codes nowadays monitoring everything from AC to windows, people sitting in seats, and the car's angular relation to the equator. Not to worry. The team at Quantrell Volvo Cars, your Volvo dealership near Louisville, will be the ultimate resource for the Volvo fault codes list specific to your car. All you need is a scanner to read them. There are a wide variety of scanners available online, from $25 to $10,000 (a $150 - $300 scanner that reads multiple systems is usually all you need).

Now that you have a better understanding of why diagnostics are so valuable, let's take a look at some answers to common questions regarding the reading, understanding, and clearing of your ECU's Volvo fault codes list.

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