Troubleshooting Fault Codes (Chrysler Two-Digit Computer Codes, 1980s-1990s)
These pages helps to describe the fault codes for the Chrysler electronic fuel injection engine control units (ECU) for 2.2L and 2.5L engines (and, in many cases, V6 engines) from 1984 through 1994. You don’t need any special computer scanners to read these codes; all you need is your ignition key.
Before we begin the process of learning what if any codes have been set in the computer, it is a good idea to understand the components involved. The primary brain of the system is the Engine Control Unit or ECU, sometimes called the logic module. The ECU is a computer with a processor, memory, and some read-only memory which holds fuel tables and other values used to make decisions about drivability and performance. It also contains the voltage regulator circuit after 1985; power circuits for ignition, fuel injection, and relay drivers. More information about the ECU to be added.
In later years, a Power Control Module is also used (it’s next to the battery), and a logic module can be found behind the passenger kickpad. It receives the engine sensor information, decides how to react, and passes signals to the PCM to adjust engine operation. In later years (1990s and up), the Power Control Module and logic module were combined into one computer, called either a SMEC or SBEC, and stored in the engine bay, usually near the battery; a Body Control Module inside the car, behind the kickpad, controls functions such as lights, power locks, and timers.
It is important to understand the different sensors. There are pages which detail each of these but here is a brief definition. Click on the name of the sensor to read a more detailed explanation.
- TBI = throttle body injection - for Chrysler, a system where a single fuel injector is used. This covers nearly all fuel-injected 2.2 and 2.5 liter four-cylinder engines that did not have a turbocharger (the exceptions were only sold in Mexico and can be treated as though they are turbocharged).
- Fault codes = two-digit codes stored inside the computer when it encounters something it did not expect (e.g. voltage where there should be no voltage).
Sensors (in no particular order):
- O2 – Oxygen sensor
- MAP - (Manifold Absolute Pressure) sensor
- Air Charge Temperature
- Coolant sensor
- Battery temperature sensor
- Detonation/Knock sensor - senses premature ignition in the cylinder
- HEP – Hall Effect Pickup or ignition reference sensor (also includes a fuel injector sync pickup sensor on turbo engines)
- TPS – Throttle Position Sensor; measures the position of the throttle opening
- Speed/distance sensor – indicates how fast the car is moving
Display your fault codes
The first step in troubleshooting drivability issues is to pull your fault codes.
Be sure the engine is not running. Then do the ‘Key Dance’. This means that within 5 seconds:
turn the key to ‘ON’ (not start) and then ‘OFF’ repeatedly, in this order: ON-OFF-ON-OFF-ON.
Be sure to leave the key in the ‘ON’ position and watch the red ‘Power Limited’, ‘Check Engine’ or ‘Limited’ light (we’ll refer to this as the ‘Power Limited’ light). One of the first diagnostic steps is to see if the light comes on at all. If it does not then you probably have a burned out bulb; replace it and start with the ‘Key Dance’ again. (If you’re a real beginner — you will find the bulb specifications in the owner’s manual.)
Looking at the Power Limited light, count the flashes. These will come in sets of two flashes. For example if you count one flash then after a pause two more that’s a code 12. This will be followed by five flashes and a pause then five more. This is a code 55 or ‘end of file’. Codes will always end in a code 55 and there will be no more flashes. This is the computer’s way of telling you that it’s all done. If the only code you receive is a 55 then you ‘have no fault codes’ and the computer has nothing to report.
Sometimes it takes a while to get used to reading the flashes, but remember that the delays are important, so watch for them — but not too hard (there are no three-digit codes!) There are also no numbers higher than 7— you’ll never see more than seven flashes in a row.
Usually fault codes will remain in the memory of the ECU for about 15 engine starts. If you want to clear these codes after you’ve repaired the system, you can do so by disconnecting the battery for a short time (which will also wipe out your radio stations; if you have a four-speed automatic, it should be retrained). The codes will usually clear in a few minutes but it may take as much as 10 minutes without battery power.
If you check the codes again after disconnecting the battery, you’ll see a code 11, 12 and 55. Codes 11 will be removed from the report the next time the engine starts, and code 12 (“battery disconnected”) after about 15 starts. Code 55 will always be reported because it’s the “end of file” indicator — it’s always there to show that you did what was needed to get a “code dump.”
When a major sensor fails, the computer will enter “limp mode.” In limp mode the computer doesn’t listen to the information from the failed sensor and relies on internal tables for things like timing and fuel delivery.
Limp mode is just what it sounds like. It allows you to ‘limp’ into the dealer or repair center to have the problem repaired. Limp mode may cause the engine to run poorly and the power limited light will be lit; four-speed automatic transmissions may be limited to second or third gear. If the power limited light comes on, check your codes to help you pinpoint where the problem is.
There is one thing to consider when troubleshooting drivability issues. Even if the computer throws a fault code it doesn’t mean that the sensor is at fault. Please read ‘How to troubleshoot drivability issues’ before replacing any parts.
The Fault Codes
Once you have taken the steps outlined in the ‘How to troubleshoot driveability issues’ and have cleared the codes by disconnecting your battery for a few minutes, if your ECU reports a code, check the links below. Each of these pages outlines the reason for the code and some information about the sensor in question. They also give information about how to further troubleshoot to see if it is indeed the sensor reported by the associated code.
|Code 11||The engine has not cranked since the battery was disconnected.|
|Code 12||The battery has been disconnected and the computer (ECU) has been reset.|
|Code 13||MAP sensor signal to the computer (ECU) not changing|
|Code 14||MAP sensor signal out of range|
|Code 15||No signal received by the computer (ECU) from the speed sensor|
|Code 16||Battery voltage drop below ‘normal’ when engine running|
|Code 17||Coolant sensor not reporting more than 160° after 8 minutes of engine running|
|Code 21||Oxygen sensor reporting too lean or too rich after 2 – 12 minutes with temp over 170° and RPM above 1500|
|Code 22||Coolant temperature sensor out of range|
|Code 23||Air charge temperature sensor out of range|
|Code 24||Throttle Position Sensor (TPS) signal out of range|
|Code 25||Air Idle Speed motor shorted or voltage out of range|
|Code 26||1985 + Turbo models: engine injector driver circuit one shorted or open
TBI models: injector peak current not achieved
|Code 27||Turbo engine injector driver circuit two shorted or open|
|Code 31||Purge Solenoid open or shorted|
|Code 32||Power Limited light lamp failure|
|Code 33||A/C relay open or shorted|
|Code 34||84 – 87 models with EGR, EGR solenoid open or shorted
1987 and later models: cruise control servo failure
|Code 35||Radiator fan relay open or shorted|
|Code 36||Wastegate or other solenoid open or shorted|
|Code 37||Baro-read solenoid open or shorted|
|Code 41||Alternator field control circuit open or shorted|
|Code 42||1984 model injector circuit 1 open or shorted
1986+ models: ASD relay open or shorted
|Code 43||Ignition coil driver circuit open or shorted|
|Code 44||1984 logic module diagnostic failure
1985-86 battery temp out of range
1987+ Signal to J2 not present at SEMC
|Code 45||Turbo engines boost above predefined range|
|Code 46||Battery charging voltage out of range|
|Code 47||Battery charging voltage out of range|
|1984 engine running too rich or lean
1985+: code 51=running too lean, code 52=running too rich
|Code 53||Logic module fault|
|Code 54||Signal loss from the fuel injector sync pickup during engine rotation. (HEP)|
|Code 55||End of fault code list|