1994 E320 Diagnostic LED Trouble

[whitleyone]

Hi to all. My CE light is on. I looked under the hood to get the codes from the LED diagnostic box and am having some trouble.

I tried to get the codes with the ignition in the on position. When I pushed the button in the first time I got nothing. When I pushed in the button and held down briefly the LED would light up and stay on. When I released the button the LED went off. No blinks. Nothing.

I cranked the car and repeated the process and same results.

I tried with the car off. When I pushed in the button you could hear a little click, the LED did not light up.

I then turned the car back on, not cranked, and figured I would try to reset the CE light. I held down the button for app. 10 secs. I then turned the car off and then on again and the light stayed on.

What am I doing wrong?

Any help is much appreciated!

Thanks in advance

[Arthur Dalton]

Key ON
Hold sw for 2-3 secs
Release
Count Flashes,

[whitleyone]

Thanks for the info. Will try again in the am. Fingers crossed.

[cliffmac]

yeah, but what's the car doing wrong that you can sense? Is it acting up?
I don't trust these warning codes; if you don't see/feel something wrong first...myself that is....I always take the position of 'thank you' telltale lights but I never put my complete trust in these tattletale lights...both on my Mercedes and BMW...good to know but not always completly accurate...

[ElRojo]

Here is a fault code list that I got from somewhere about a year ago, and I'm pretty sure this applies to the 320 you have.

Display Diagnostic Code
1. turn-engine off;
2. turn ignition switch to #2 position (do not start car);
3. depress switch (at diagnostic port) for 1-second, then release;
4. count number of LED blinks before going to solid/always on;
5. depress switch again to see if there are any other faults in memory (faults are displayed in descending order, and if there are no other faults in memory, the first fault number should re-appear);
6. record the number of blinks you counted for history;

Erasing/Resetting Check Engine Light
within 20-seconds of LED going to solid/always on,

1. depress switch for 6-10 seconds, release;
2. LED should blink ONCE then go to solid/always on;
3. turn ignition switch off;
4. restart car and verify that Check Engine Light is OFF (assuming you have CORRECTED the problem).

Here are the error codes.
Count the blinks after pressing the diagnostic button for 1 sec.

1. No Malfunctions;
2. Full load contact, throttle valve switch implausible;
3. Coolant temp. read by CIS-E implausible;
4. Potentiometer voltage implausible;
5. O2-sensor signal implausible;
6. Not Used;
7. TNA-signal (RPM-signal) read by CIS-E implausible;
8. Altitude pressure signal from EZL control unit implausible;
9. Current to EHA is implausible;
10. Idle contact, throttle valve switch implausible;
11. Air Injection System;
12. Absolute pressure values from EZL is implausible;
13. Intake air temp. reading is implausible;
14. Speed signal read by CIS-E is implausible;
15. Not Used;
16. EGR
17. O2-sensor line shorted positive to ground;
18. Current to idle speed air valve is implausible;
19. Not Used;
20. Not Used;
21. Not Used;
22. O2-sensor heating current implausible;
23. Short circuit to positive in purge switchover valve circuit;
24. Not Used;
25. Short circuit to positive in start valve circuit;
26. Short circuit to positive in shift point delay circuit;
27. Data exchange between CIS-E unit & EZL unit interrupted;
28. Intermittant contact in coolant temp. sensor circuit;
29. Difference in coolant temp. read between CIS-E unit & EZL unit;
30. Not Used;
31. Intermittant contact in intake air temp. sensor;
32. Not Used;
33. Not Used;
34. Coolant temp. from EZL unit is implausible.

[Arthur Dalton]

<
>>

Does not apply...he has HFM/SFI with DIS Ign, not EZL systems.

[whitleyone]

Thanks again for all the info.

I tried again today and did it right and pulled a code 4, which is the MAF sensor from a chart I found over at benzworld.org. I'll post the codes below for anyone else who has an E320 that needs these for diagnosis. Thanks to jayare over there for the info.

And thanks to you Arthur for your input. I always look to your posts as they are spot on and helpful.

Here are the codes (all of them):

Emissions - Using Built-in Diagnostic Module
1 No Fault Found
2 Heated oxygen sensor faulty
3 Lambda control faulty
4 Air injection system faulty hot film mass air flow sensor with hot wire
5 Exhaust gas recirculation faulty
6 Idle speed control faulty
7 Ignition system faulty
8 Engine coolant temperature sensor open circuit
9 Intake air temperature sensor, open circuit
10 Voltage at mass air sensor too high/low
11 Tn-signal (rpm signal ) at engine control module faulty
12 Heated oxygen sensor heater circuit open or circuit short
15 Injector, cylinder 2
16 Closed throttle position information faulty
17 Data exchange malfunction between individual control module
18 Adjustable camshaft timing solenoid circuit open or circuit short
19 Injectors circuit open or circuit short emission control module adaptation in engine
control module at limit
20 Vehicle speed signal not present
21 Purge switchover valve circuit open or circuit short
22 Crankshaft position sensor signal faulty
23 Intake manifold pressure (in base module pressure sensor-) with engine running too
high/low.
24 Starter ring gear segments and /or crankshaft position sensor faulty
25 Knock sensors or engine control module faulty
26 Upshift delay faulty
27 Not used
28 Engine coolant temperature sensor (engine coolant temperature change monitor )
44 Not used
45 Fuel safety shut-off electronic accelerator or cruise control active
46 Resonance intake manifold switchover valve
47 Not used
48 Not used
49 Voltage supply at engine control module 8v
50 Engine control module
_________

PIN 8 ECU
1 No fault found
2 Engine Coolant temperature sensor
3 Intake air temperature sensor
4 Hot film mass air flow sensor
5 CTP switch
6 Not used
7 Not used
8 Idle speed control (ISC) system at upper or lower control stop or CC or EA indicates "limp
home" mode.
9 O2S 1 (before TWC) - voltage too high, circuit open or voltage implausible
10 O2S 2 (after TWC)voltage too high, circuit open or voltage implausible
11 O2S 1 heater (before TWC) - Current too high/low or short circuit.
12 O2S 2 heater (after TWC) - Current too high/low or short circuit.
13 O2S (Lambda) control system operating at rich or lean limit
14 Injector, cylinder 1
15 Injector, cylinder 2
16 Injector, cylinder 3
17 Injector, cylinder 4
18 Injector, cylinder 5
19 Injector, cylinder 6
20 Self-adaptation at idle speed or upper/lower partial load at rich or lean limit
21 Ignition output 3 or ignition coil for cylinder 1 and 6
22 Ignition output 1 or ignition coil for cylinder 2 and 5 (Engine 111, cylinder 1 and 4)
23 Ignition output 2 or ignition coil for cylinder 3 and 4 (Engine 111, cylinder 2 and 3)
24 CKP sensor or magnet for position sensor not recognized
25 CMP sensor not recognized or implausible
26 Not used
27 TN-signal (rpm signal ) - open or short to ground
28 VSS - open circuit
29 Not used
30 Fuel pump relay module - open or short circuit
31 Not used
32 Knock sensors 1 and /or 2
33 Maximum retard setting on at least one cylinder has been reached or the ignition angle
deviation between the individual cylinders is greater than 6 degrees crankshaft angle
34 Knock control-output switch in engine control module faulty Momentary fault in
self-adaptation closed throttle speed/partial load
35 Model 124,129 and 140 AIR pump switchover valve and/or electromagnetic AIR pump
clutch. Model 202 AIR pump switchover valve and/or AIR relay module
36 Purge control valve - open/short to ground or B+
37 Upshift delay switchover valve
38 Adjustable camshaft timing solenoid - open/short to ground or B+
39 Exhaust gas recirculation switchover valve - open/short to ground or B+
40 Transmission overload protection switch - open/short to ground or B+ or open or closed or
implausible
41 CAN communication from engine control module faulty
42 CAN communication from ASR, EA/CC/ISC module or diagnostic module (OBD II) faulty
43 Starter signal (circuit 50) not present
44 Not used
45 Fuel safety shut-off of electronic accelerator or cruise control active
46 Resonance intake manifold switchover valve - open/short to ground or B+
48 O2S 2 (after TWC) heating circuit relay module - open/short to ground or B+
49 Voltage supply at engine control module implausible/low volts
50 Engine control module faulty or not coded.
____________

PIN 14 CC/ETA
1 No fault found
2 EA/CC/ISC control module (N4/1) or Safety contact switch (M16/1s1) or Stop lamp
switch or Cruise control switch or Actual value potentiometer or Starter lock-out/back-up
lamp switch or engine speed signal or vehicle speed signal or closed throttle position
switch or safety relay in EA/CC/ISC control module
3 Right EA/CC/ISC actuator (left cylinder bank) (M16/1)
4 Cruise control switch (S40)
5 Stop lamp switch (S9/1)
6 Starter lock-out/backup lamp switch
7 CAN data bus signal from EA/CC/ISC, ABS/ASR, HFM-SFI or LH-SFI (right or left)
control module faulty.
8 Left front axle vehicle speed sensor from ABS/ASR control module
9 Left rear axle vehicle speed sensor from ABS/ASR control module or in 124 chassis
Hall-effect speed sensor.
10 Engine speed signal (TN) from base module (LH-SFI) or engine control module (HFMSFI)
11 Closed throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI)
Fuel safety shut-off to engine control module (HFM-SFI or left or right LH-SFI)
12 EA/CC/ISC control module voltage supply
13 Left EA/CC/ISC actuator (right cylinder bank) or actual value potentiometer (M16/4r1 or
M16/4r2) or actuator motor (M16/4m1)or magnetic clutch (M16/4k1).
14 Closed throttle position contact switch
15 CAN data exchange with ABS/ASR control module illogical

[Arthur Dalton]

We have those codes here,[ that's where they got them from].. but your problem is more likely the AIR system.
On that chassis , the vac hose that feeds the AIR SOV valve [ under the front engine cover] is plastic and they crack from heat fatique..I would look there first.
The ECU looks for a lean mix from the 02 sensor to test AIR system.... so it is Failing that self-test.

E320 16 PIN DTC Charts inc. pin 8, pin 14

What you want now is the real codes from the Engine Mangemant modules.

You have only accessed the Emmissions N/59 module.

[whitleyone]

Funny you should mitchen the SOV. I am assuming that is the switch over valve? I replaced the wiring harness app. a month and a half ago and did indeed break the briitle air tube that went to the aforementioned valve. Went to the dealership and they had to special order the tubing. Of course the check engine light came on in the meantime. After replacing the tubing to the SOV the light stayed on for another day or two and then turned itself off.

About a week ago the CE light came on again. I pulled the MAF to see if there was any dirt or build up visible to the naked eye and all looked clean. Reset the CE light so we'll see if it comes back on.

Can the MAF be cleaned with carb or brake cleaner as I think I read somewhere on this forum as a start if the code is thrown again?

[Arthur Dalton]

MAF Cleaner ...any auto store.

But, the point I am making to you is that experience says that code from DM is almost NEVER a MAF code , it is an AIR code.

So, you now look at the real code storage and see what is there ..you then couple that with the DM codes for a better diagnosis.. if you see an 02 sensor code at 8, then you know that is why you have a 4 code at DM...etc , etc , etc,
If you MAF is the problem, it will have codes in the HFM module.

The codes at the DM are just codes that wind up there from the other modules b/c they will effect Emmissions..they are not engine management codes.

If you want to find the Reason for a DM code, you go and get the individual diagnostics codes in the running modules..the DM is just a CE lamp activation module that says you have an Emmission related fault.

[whitleyone]

Thank you. Will check the other codes, or get the dealer to, and find out the cause of the CE light.

Invaluable information!!

[Arthur Dalton]

For $10 you can make that simple tool I posted and get them yourself.
Your chassis is the last of Flash Code [ OBD1] , and it is a good tool to have as long as you are going to own one of these owner code accessible chassis.

The modules with fault code storage memory are right there and it is quite simple to go get them, so why guess when you have a computer monitoring the systems at all times for you.??

Here is a good Hypothetical Diagnosis example using the Code system.

You get a CE lamp.
You go to the DM push-button and you retrieve a code #7 .
You check the DM chart -Ign System fault.
But that only tells you that there has been an Ign problem detected and that info has been passed on to the DM. And b/c an ign failure can effect the Emmissions Mandates of that vehicle, a CE warning lamp is activated by the N/59 module [ DM]
Now we want to know more about this Ign. problem....

..so.................

.... We take the tool and go into the HFM module where the ign system is monitored [pin 8] and guess what comes back ???..... a code 21 ..we look that up in the chart, and guess what we find ..the HFM module has detected a failure in the #3 coil. [ cyl 1 & 6]. How nice !!!
Much better info . We can now fix the underlying problem , get rid of the CE , and have the car and it's faults done with...problem solved.
You could have just cleared the CE w/DM button, but it would come back b/c you have not found , or pin-pointed , or solved the problem.

The tool also allows you to reset the Memory of the Modules ...pretty cool for the year. There are times when a part change requires the re-setting of the ECU to mean adaptation values. The tool will also do this procedure.

Here is some more good code info for that generation/vintage years of Benzs.

http://www.geocities.com/MotorCity/Downs/1039/mercedes/cs1000_mb.pdfinfo.

The Correct code chart , [ make sure of that cuz there are hundreds of codes and very system/chassis specific], the tool, and a post or two here will keep your trips to the Dealers down to a minimum..,and you may even wind up with a more accurate diagnosis. ..and save a few $$$$$$, sometimes Many ..............................................

[whitleyone]

I think that's a must do. Thanks for the advice and I'll send a pic of my code reader when made.

[tan man]

Arthur, how would I proceed if I get code 4 from the CE module and code 13 from pin 8?
The car is a 1995 E320.
Thanks in advance

[Arthur Dalton]

My first check on code 13 would be to look for a vac leak ,and take the vac line off the Fuel Pressure reg and see if gas comes out that port when at idle.
The car is trying to adapt to an out of wack a/f mix and has reached it's limits, meaning it can not correct . Could also be too high a fuel pressure.
Check the reg first. 02 sesnor could be carboned up from reg and when the car does the AIR test, 02 can not respond to full lean condition of test, so the AIR code follows the 13 code.
Of course , also check that the air pump is coming on., etc.........