1992 500E CEL Fault 7 TN-Signal

[marcelk]

Hello, new to this site. I am posting on behalf of my father since he is not that great with computers and forums. He has a 1992 500E that has been siting for 3 years and now we are trying to get it back running and smoged. Problem is the CEL is on and has the fault code 7 tn-signal(rpm-signal) incorrect or open/short circuit and won't go away. The car runs fine, idles fine, rpm signal in the tach works, i check the crank position sensor resistance and measured 822ohm. I tried google but couldn't find anything really. Any help and input would be highly appreciated. Thanks Marcel.

 

[Glen]

Code 7 on the diagnostic module is ignition system defective. You are looking at the code for pin4 not pin19 which is the diagnostic module.

 

[gsxr]

Glen is correct. CEL blink code #7 is "Ignition system defective", not "tn-signal(rpm-signal) incorrect or open/short circuit "; the latter would be code #11.

I don't know what code list you are using to translate the blinks but please read the 3 sticky topics/threads at this URL, specifically look for the PDF file attached in the first post of the first thread titled "DTC_List_W124_M119.pdf":
http://www.500eboard.com/forums/forumdisplay.php?f=23

The CEL is triggered by the Diagnostic Module only, which is pin #19. The built-in LED in front of the CAN box only shows codes from DM / pin 19, nothing else. Strange that the car is running normally, if you can't clear that code.

BTW - welcome to the forum!

 

[marcelk]

Okay thanks for the tip. Any idea where to start looking in the ignition system, wiring or the module? Thanks

 

[gsxr]

First thing to do is get a blink-code reader and check codes on pin #17 which is the EZL / DI (Digital Ignition) module. That may provide additional clues as to what is causing the CEL.

I would also triple-check that it is indeed code 7 from the DM; also make sure you are using the proper procedure to clear the code.

 

[marcelk]

okay, thanks. I will get to it after the holiday again and keep the thread updated

 

[samiam44]

Not that it will help.. wed love if you post the Vin and a few pic.

I think the cps at the flywheel and knock sensors are the main inputs. Dave knows his stuff. Buy or make a code reader.

M

 

[marcelk]

Hello, sorry for the late response, so i bought the code reader like suggested in the DTC list thread. Scanned the car and the faults were actually for the secondary air and egr solenoids which were disconnected, after fixing that and clearing the faults the check engine light stayed off. The car has another problem now doe i don't know if i should make a new thread for it or just keep posting in here. So my dad started driving the car and he said that when he was turning all the warning lights in the cluster started glimming and then turning on and then of again after a bit but now they are all on except the check engine light, srs and oil level light and on all the time.

 

[marcelk]

So after searching the threads i the forum i found the common problem apparently is the alternator or vr so i checked the charging system and the voltage is 11.7 Volt, gonna replace the vr first to see if it fixes it