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Archive-name: autos/chrysler-faq/general/part3
Posting-Frequency: 15 days
Last-modified: 2004/4/13
Version: 4.5

See reader questions & answers on this topic! - Help others by sharing your knowledge
Modifications and detailed fixes are at the web site -

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See the very last part of this section for reading ESA computer codes
without a scan tool! Useful for those without the key-turn-watch-light
feature (e.g. 1985 Caravans) -- and those with it!

Note that engine codes have been updated since this list was created. See for an updated list.

          1. Engine Codes
          2. [Outdated and removed]
          3. Classic Car Troubleshooting
          4. Reading codes without a scan tool
              (computer controlled, carbureted engines)
          5. Crankcase inlet air filter, 2.2/2.5 engines.

  While effort has been taken to insure the accuracy of the   information
contained in this FAQ list compilation, the author and   contributors
assume no responsibility for errors or omissions, or for   damages
resulting from the use of the information.   The information may be
reproduced IF    credit is given to the writers and the maintainer; and
that it is not   published without the prior written   permission of the
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copy of the final material; and that no changes   are made without the
express permission of the maintainer (David Zatz who is at
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  The latest copy may be obtained from
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FAQ for  -  Part III


THESE ONLY WORK IF YOU HAVE FUEL INJECTION. Otherwise, see the web site or
the "troubleshooting electronic feedback carburetors" section.

Start with the ignition off. Within five seconds, switch the key on, off,
on, off, on. (On is *not* start!)

The "check engine" light will flash. Count the flashes Each code is a two
digit code, so a (for example) 23 would be FLASH FLASH <pause> FLASH FLASH
FLASH <loong pause>

It will never flash more than 9 times, watch for pauses!
55 is end of codes, 33 is normal if you don't have air conditioning.

When the computer indicates major failure, it will activate Limp In mode,
which guesses about data to compensate for sensor failure.


See for a new, revised list of
computer codes and instructions on how to get them. These codes appear to
have been phased in starting in around 1998.


Please note that some codes are NOT included below, this is not a complete
listing. (From Herb with additions by Charles Hobbs. Basis: Mopar Mailing
List info.)

* Activates Power Limited/Check Engine light.

11  No ignition reference signal detected during cranking (bad Hall
    OR timing belt skipped one or more teeth;
    OR loss of either camshaft or crankshaft position sensor
12  Battery or computer recently disconnected
    - Fraser Shortt said code 12 appeared with some other codes
      in 1989 and possibly later computers as well.
13* MAP sensor or vacuum line may not be working
14* MAP sensor voltage below .16V or over 4.96V

NOTE - on early Neons, a computer error may light the Check Engine light and
show one or more of these codes. If this happens, bring it in so the dealer
reprogram the computer (about ten minutes).

15  No speed/distance sensor signal
16* Loss of battery voltage detected with engine running
17 (1985 turbo only): knock sensor circuit
17  Engine stays cool too long (bad thermostat or coolant sensor?)

21  Oxygen sensor signal doesn't change (stays at 4.3-4.5V)
     Probably bad oxygen sensor
22* Coolant sensor signal out of range
     - May have been disconnected to set timing
23*  Incoming air temperature sensor may be bad
24* Throttle position sensor over 4.96V (SEE NOTE #3)
25  Automatic Idle Speed (AIS) motor driver circuit shorted
    or target idle not reached, vacuum leak found
26  Peak injector circuit voltage has not been reached
     (need to check computer signals, voltage reg, injectors)
     (SEE NOTE #4 BELOW)
27  Injector circuit isn't switching when it's told to (TBI)
     OR (MPI) injector circuit #1 not switching right
     OR  (turbo) injector circuit #2 not switching right
     OR (all 1990-) injector output driver not responding
     - check computer, connections

31  Bad evaporator purge solenoid circuit or driver
32 (1984 only) power loss/limited lamp or circuit
32  EGR gases not working (1988) - check vacuum, valve
32 (1990-92, all but Turbo) computer didn't see change in
     air/'fuel ratio when EGR activated
     - check valve, vacuum lines, and EGR electrical
33  Air conditioning clutch relay circuit open or shorted
     (may be in the wide-open-throttle cutoff circuit)
34  (1984-86) EGR solenoid circuit shorted or open
34 (1987-1991) speed control shorted or open
35  Cooling fan relay circuit open or shorted
35 (trucks) idle switch motor fault - check connections
36  (turbo) Wastegate control circuit open or shorted
36 (3.9/5.2 RWD) solenoid coil circuit (air switching)
36 (Turbo IV) #3 Vent Solenoid open/short
37  Shift indicator light failure, 5-speed
    part throttle lock/unlock solenoid driver circuit (87-89)
     solenoid coil circuit (85-89 Turbo I-IV)
    Trans temparature sensor voltage low (1995 and on; see NOTE 2)

41* Alternator field control circuit open or shorted
42  Automatic shutdown relay circuit open or shorted
42 Fuel pump relay control circuit
42 Fuel level unit - no change over miles
42  Z1 voltage missing when autoshutdown circuit energized (SEE NOTE #6)
43  Peak primary coil current not achieved with max dwell time
43 Cylinder misfire
43  Problem in power module to logic module interface
44  No FJ2 voltage present at logic board
44  Logic module self-diagnostics indicate problem
44  Battery temperature out of range (see Note #1!)
45  Turbo boost limit exceeded (engine was shut down by logic module)
46* Battery voltage too high during charging or charging system
    voltage too low
47  Battery voltage too low and alternator output too low

51  Oxygen sensor stuck at lean position (lean condition)
51  Internal logic module fault ('84 turbo only)
52  Oxygen sensor stuck at rich position  (SEE NOTE #5!)
52  Internal logic module fault ('84 turbo only)
53  Logic module internal problem
54  No sync pickup signal during engine rotation (turbo only)
54  Internal logic module fault ('84 turbo only)
55  End of codes

61  "Baro" sensor open or shorted
62  EMR mileage cannot be stored in EEPROM
62 PCM failure SRI mile not stored
63  Controller cannot write to EEPROM
64 Catalytic converter efficiency failure
65 Power steering switch failure

88  Start of test (not given on most computers)

NOTE #1.

The power module has an air-cooled resistor which senses incoming air
temperature.  The logic modules uses this information to control the field
current in the alternator.  This code applies ONLY to alternators whose
voltage is computer regulated.  If you lose the feed to keep RAM
information stored
when the engine's off, you also lose battery voltage sensing.  -- Bohdan Bodnar


From the 1995 TRUCK manuals: the trailer towing package includes a
transmission coolant temp sensor while the standard package doesn't.
This may cause the low (no) voltage indication.   -- J.E. Winburn


Matt Rowe comments:  The throttle
postion circuit tells the computer how far the accelerator is depressed.
The Throttle Position Sensor (TPS) is on the throttle body on
the opposite side of the throttle cable.  The connector should
have a round rubber cover over the connections.  Clear the fault
codes, start the car and try jiggling the wires/connectors to try
to trip a fault code.  Loss of this signal could cause other problems.


During  cranking, the computer will test the current through the
injector to see whether there's too much resistance in the injector's
path.  If there is, code 26 is set.
       The problem may be cured with tuner cleaner on the connectors.
       For TBI engines, the injector's cold resistance should be between
0.9 and 1.2 ohms (specs vary with year).  This is a peak-and-hold
injector.  With the engine idling the
peak period should be about 1.2 milliseconds whereas the hold period
will vary.  If it's lower than this at idle, then the injector's shorted or
there's a defect in the injector driver circuit. (Bohdan Bodnar)


Wade Goldman wrote: In my case, the breather tube leading into the
catalytic converter had rusted and become detached.  This some how would
cause the sensor to read an over rich condition and run crummy. I did not
trust the reliability of the weld over a  corroded surface and opted for
the more expensive route of replacing the converter, breather tube and all.


The Z1 voltage is the voltage of the circuits fed by the autoshutdown
relay.  This typically includes fuel pump and switched-battery feed to the
ignition coil(s). In my Le Baron, the Z1 circuit leaves the power module
and splits into two paths:  the fuel pump and the positive side of the
ignition coil.  Internal to the power module is the auto shutdown relay (in
my case, it's a sealed box about 1" by 1").  The output voltage is
monitored to determine whether the relay responds correctly.  I suspect
that the ASD relay (and, therefore, the Z1 circuit) also feeds the fuel
injector(s) driver(s) and current sensing circuit, but can't prove this.

I've used the Z1 voltage to test for good power connections to the power
module. I connected my OTC 500 multimeter from the battery's positive post
to the ignition coil's switched battery terminal and measured the voltage
drop using the bar graph to monitor peak voltages.  Voltage spikes of
around 200 mV to 300 mV are ok -- anything more means tv tuner cleaner time
(or replacing the power module).  Another thing to check is the maximum
voltage drop during the priming pulse.  With the old power module, I was
losing about 2 volts across the circuit;  the replacement is losing about
1/4 volt.  (Thanks, Bohdan Bodnar)

**************** CLASSIC CAR TROUBLESHOOTING ****************
(1950s-some 80s)


Many of these were taken from the A-Bodies site at

C1. Won't start (<Dave>):

Check the ballast resistor. It's a little white block attached to the
metal between the engine and the driver, with a single bolt; wires plug
into each side. It's easy to replace and under $5.

If the starter makes a rapid clicking noise, your battery may be worn, even if
you can see your headlights.

If the engine was wet, dry it, separate the wires, and try again, Use
silicone spray or "wire drier" or, better yet, replace your wires with
really good ones ($25-40 mail order). These will probably improve your gas
mileage and power as well.

Dan Stern adds: Whitaker's Multi-Mag comes in the same colors and
insulation materials as original, but uses the spiral-wound
construction that you find in wires such as Accel and Jacobs. Lower
resistance, but no irritating radio noise. They have a lifetime guarantee
and don't cost more than regular carbon-string type wires. The
Slant-6 wire set (32605 for pre-75) has the correct 1-piece moulded
plug boots.  They are also sold under the Borg Warner/BWD KoolWire name.
C2. Anything from pollution to loss of power (<Dave>)

This may be caused by leaking vacuum hoses or mechanics
disconnecting your vacuum hoses. If you like to breathe, and you want
your car to perform well, replace all of the vacuum hose -- it costs
maybe 10 cents per foot. Just get a few yards and do
it one day (warning: you may need different kinds or sizes. You may need to
bits of the old stuff into the shop). Make sure hoses are not kinked.

Vacuum leaks caused by leaking hoses that look okay to the naked eye may
result in the following diagnoses by mechanics:
* Need new carburetor
* Need new transmission
* Need new engine
* Need valve job
* Need new mechanic.
C3. Stalling (<Dave>)

See the above section on vacuum hoses. Turning the cold or warm idle
screw on the carburetor is a quick fix that doesn't solve the real
problem. If the car stalls when cold, lubricate the choke well. If it
stalls when wet, try getting much better ignition wires (lifetime
warranty, good brand, about $30). Also try:
* Put window insulating tape (foam) over the top of the electronic
ignition module
* Spray the little wires with silicone spray or wire drier
* Check for vacuum leaks (see above).
C4. Windshield wipers won't work ():

Put window insulating tape (foam) over the top of the wiper motor.
C5. Water leaks into the car:

A problem on many A-bodies (Valiant/Dart group). May be solved by keeping
the cowl (that grille between the hood and windshield) free of leaves and
gunk, and by  straightening out and emptying out the air conditioner
condensation drain. The black tube that carries a/c water may be seen on
the firewall (the metal between the engine and the driver). It is small and
behind other stuff. Sometimes the end of this black tube freezes to itself
and must be opened with a knife or razor.

C6. runs rough cold, seems to improve with heat

George Young suggests:
1) Not enough voltage from old damp coil?  - new coil.
2) EGR valve plunger binding open?
   - remove and plug manifold vacuum hose to EGR circuit.

Dave adds: Better wires, high quality rotor/distributor cap for
best fit. Check the stove, that big metal thing on many engines that feeds
warm air from the engine to the air intake through a usually-rotten or missing
hose. The vacuum-operated flap may also not be functioning for one reason or
another, usually a bad vacuum hose. This is common. Dan Stern notes the flap is
controlled by the Thermostatic Air Cleaner vacuum motor...

George Young adds: My old 318 ran rough when cold and
wet, would stall out until warm.  Choke was the problem.  Manifold
carboned up and wouldn't pass heat to choke coil thermostat.  Changed to
manual choke and no more problem and increased gas mileage

Dan Stern noted that driveability problems could be caused by a bad choke
control unit, which may short out and shunt full power to the electric choke,
causing it to heat up prematurely.
C7. Lean-Burn (computer-controlled carbureted engine) rough idle

1). Are your coolant temperature sensor connection ok?  If not, the
computer will see a cold engine and will run rich.
2). Are the oxygen sensor connections ok?
3). Is the heated air inlet operating correctly?
4). Vacuum leaks?  Check all vacuum hoses with a religious fervor!
    The leak's location many not even be obvious!
5). Carburetor problems:  float low?  valve seat damage?  I doubt the
latter since it appears that the problem arose quite suddenly. The
following is something I've used on computer-controlled carbureted
engines many times: 1). Connect a high impedance dwell meter to the
mixture control solenoid, set the meter to the 6 cylinders scale, run
the engine around 2000 rpm until hot and see the dwell.  If the a/f
mixture's ok, you'll see the dwell oscillating about 30 degrees.  Low
dwell with oscillations => a/f mixture lean and running closed loop.
High dwell with oscillations => a/f mixture rich and running closed
loop.  Dwell at or below 10 degrees => system stuck lean.  Dwell at or
above 50 degrees => system stuck rich.  The latter two extremes indicate
closed loop operation since open loop operation typical will show a
stable dwell reading between 20 and 30 degrees (usually, closer to 20).
Do not do this test at idle since some engines will be operated in open
loop at idle REGARDLESS of the coolant temperature sensor's output.
Incidently, I've just outlined the procedure for GM's "System
Performance Test" which is used on GM C3 carbureted engines.
C8.   Gas gauge acts funny: See #34. (part 4)
C9. Stalling or poor idle - wet weather / snow -- see #39 (part 4)
C10. Slant Six problems

Cold driveability problems tend to stem from poorly
adjusted choke and choke pulloff, bad accelerator pump, and sloppy carb
(Carter BBS one barrel is better than Holley 1920.)
Other big driveability problem source is the fact that the vibration
damper outer ring tends to slip, which makes the timing mark WAY OFF. Which
means timing would never be accurately set.  Also check for timing chain

Check by putting the engine at #1 TDC - top of compression stroke (both valves
closed) and see where the timing mark is.  There are companies that re-bond
dampers with new silicone material.  I think one is called Damper Dudes,
out of
California. I don't know if this happens on other CC engines.  Basically, if
your damper has an inner hub and an outer ring sandwiching rubber bonding
material, this can happen.

C11. 318 V8 troubleshooting

Bruce Martin wrote:
One very common fault with the otherwise wonderful 318 is that the
exhaust crossover in the intake manifold (which warms the base
of the carb) becomes clogged. This is common so it should be
among the first things you check. (This problem was addressed on the
Magnum engines)

It is interesting the wide variety of timing specs given for the 318, all the
way from 2 degrees ATDC to 16 degrees ATDC, depending on the type of engine
vehicle...Most books recommend not to try to time by ear, even if you have
experience doing this.

Ted Devey adds two more steps:
1. examine the reluctor teeth in the distributor for possible damage,
nicks etc. which can happen if the gap gets too small. If there is damage
to the
teeth, replace the reluctor.

2. Several years ago I dismantled the Carter 2-barrel carburettor and
reassembled it with the jet assembly upside down. There is no obvious wrong

C13. Seat belt looseness

During the late 70's up through the late 80's all American cars had
something called a window shade mechanism to allow for a small amount of slack
to build-up in the shoulder belt.  This was to prevent people from complaining
that their belts were too tight.  I experienced (ref:June '87 Car and Driver
article by Patrick Bedard) a problem where the seatbelt built up too much
Sometimes the belts, like a windowshade, would never return at all.  There is
usually a large plastic button on the 'B' pillar that needs to be fooled into
thinking the door is always opened, which by the way disables the window shade
mechanism and is how the belts return 'home' when you get out of the car.
the plastic button very close to the 'B' pillar, being careful not to cut into
the inner spring
Take a  cotter pin and put it through the loops of the spring, this
prevents the
spring from ever retracting.  Chrylser mini-vans are easier in that they
have a
rotating plastic cam with a striker pin that is engaged by the closing door.
Just cut the striker pin and you eliminate the problem.
C14. Low front end

Many late 60's and early 70's A-body Chrysler products had a problem
with the rear mount for the torsion bar. Water collects in the channel
and rust occurs. After a decade or so the channel that the mount is
welded into rusts through and the mount twists and that side of the
car falls onto the rebounce (sp?) bumper. If this is what happened you
will need to find a local frame/suspension/alignment shop that has
someone who has welded in new material to replace the rusted stuff and
then realign the ride height when done. (Thanks, Chris Jardine).

C15. Pinging on V-8s

Pete O Dickerson wrote: My 75 Dodge Swinger 318 would ping at part throttle
operation, not at full  throttle (floored!) like you might expect.  Just going
over an overpass or up a hill the engine would ping and clatter, even
though the
ignition timing and carburetor were set correctly.

The manifold was made from cast metal.  The molten metal was poured into a
through a little hole and when the manifold was finished, the little hole was
plugged up with a little rubber plug.  Well, after a few years this little
would dry up, shrink, and fall out, leaving a hole in the manifold.  This hole
would cause a lean condition to exist at part throttle operation, by
letting air
leak in.

Try removing the carb and shining a flashlight down into the manifold and
if there is a hole in the bottom of the manifold.  You can either plug it
up or
replace the manifold with a more performance oriented unit.

(The maintainer adds: invest in a vacuum gauge, they are cheap!)
C16: Fast idle, then stalling.

>From Timothy Economou: If you start your car and it runs for a while at fast
idle and then it starts to load up and then stalls.  There is this little
thing on the open end of your breather that closes the outside air when
your car
is at fast idle and lets it draw air from the manifold. (Stove control). Check

Editor's note: the stove control is frequently bad on vintage vehicles. The
vacuum hose, control, and mechanics of the flap in the air horn should be
checked. See above.



From: Bohdan L Bodnar

This is the procedure I've used to diagnose air/fuel
mixture problems in computer controlled carbureted engines;  the
procedure can also be used to set the idle air/fuel mixture
without exhaust gas analysis.  The procedure is
based on the General Motors System Performance Test.


The a/f mixture is controlled by a MIXTURE CONTROL SOLENOID (MC
solenoid). This is a valve which operates at a fixed frequency
(typically, 10 Hz) and whose duty cycle (valve's ON time divided by
period) is varied.  That is, the valve is pulse width modulated.  When
the valve is turned on, the incoming a/f mixture is fully leaned;  when
off, fully enrichened.  The former is called a "lean command" whereas
the latter is called a "rich command."  By varying the duty cycle of the
MC solenoid, the AVERAGE a/f mixture can be varied.  In GM products,
this valve directly varies the incoming fuel and air flow.  In Chryslers, only
incoming fuel flow is directly varied.

The valve has a two wires electrical connector.  On wire is connected to
switched battery voltage whereas the other is connected to a power
transistor in the computer and is a source of switched ground.

During closed-loop operation the following will occur (assume the oxygen
sensor is sensing a lean condition -- its voltage will be low):

1). The computer gradually decreases the MC solenoid's duty cycle.

2). The exhaust eventually becomes rich enough that the oxygen sensor's
output will swing high (about 1 volt).

3). The computer gradually increases the MC solenoid's duty cycle.

4). The exhaust eventually becomes lean enough that the oxygen sensor's
output will swing low (about 0 volt).

The cycle now repeats.  A device for monitoring the solenoid's duty
cycle (such as a dwell meter) will show a constantly varying duty cycle.
The frequency of the oscillations will depend on the how fast the
computer varies the duty cycle and the engine's RPM.  An AVERAGE duty
cycle of 50% corresponds to, on the average, NO average a/f correction.
Stated differently, everything is operating correctly.  An average duty
cycle of LESS THAN 50% corresponds to, on the average, a rich command
(the computer is compensating for a lean condition).  An average duty
cycle GREATER THAN 50% corresponds to, on the average, a lean command.


Monitoring the MC solenoid's average duty requires (for most people) the
use of high impedance dwell meter. A low impedance dwell meter may be
used unless it affects engine operation;  stay away from self-powered
dwell meters.  Following the GM procedure, set the dwell meter to the
six cylinders scale REGARDLESS of the number of cylinders in the engine.
At this setting, 30 degrees will correspond to a 50% duty cycle, 60 to a
100% duty cycle, and 0 to a 0% duty cycle.  Run the engine until closed
loop operation is present;  this will be indicated by a varying dwell
(see footnote 1 for deviations from this procedure).  Once the engine is
hot, not the average dwell -- the reading should vary equally above 30
degrees and equally below 30 degrees.  The following is a brief trouble

1). DWELL NOT VARYING:  system is operating in open loop.

2). DWELL STUCK AT 10 DEGREES OR LOWER:  full rich command is present;
the computer is compensating for WHAT APPEARS TO BE a massive fuel flow
reduction (check for dirt in carburetor, air injection system stuck in
upstream position, vacuum leaks, improper a/f mixture setting...).

3). DWELL STUCK AT 50 DEGREES OR UP:  full lean command is present
(check for float stuck low, valve seat damage, oxygen sensor's sense
lead shorted to battery voltage, etc.)

rich command is present (check for vacuum leaks, dirt in carburetor's
jets, improperly set a/f mixture...)

lean command is present.  Check for incorrectly set a/f mixture, float
stuck low, valve seat damage, clogged air filter, etc...).

Based on the above descriptions, it should be fairly clear on how to set
the idle a/f mixture:  merely set the mixture so that the average dwell
is 30 degrees.  Now, suppose the system's dwell is not varying, but the
sensors are working properly, the upper radiator hose is hot...

Several cars with small engines have the oxygen sensor mounted fairly
far away from the engines.  During idle conditions, the sensor
may cool off to the point that it will not operate.
Turn off all electrical accessories (so
as to provide a minimal load on the engine) and use the idle stop screw
on the carburetor to gradually increase the idle rpm until the sensor
begins oscillating.  Ensuring a negligible load on the engine guarantees
that the carburetor will be operating mostly on its idle circuit.  Now,
set the a/f mixture so that the average dwell is 30 degrees.

Note that the a/f mixture setting procedure assumes that NO fuel
delivery problems (vacuum leaks, clogged carburetor, etc.) are present.


[1]  In some engines the a/f mixture is varied REGARDLESS
of whether the engine is in closed loop operation or not.
Consider setting the a/f mixture or diagnosing
at a slightly increased rpm.



If you remove the air cleaner and look at it from the front, the
breather (crankcase filter) will be in the "box" at the lower right
side.  To get at it, you remove the 8 or so machine screws and the
bottom of this "box" will fall off.  The filter is held in place by a
crudely placed screen.  Lee makes a replacement filter (about
$2).  In my Le Baron, I ended up replacing all the screws with
self-tapping sheet metal screws since the factory had almost every one
overtightened.   --- Bohdan Bodnar

David Zatz works at

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