420 Check Engine Light
Thread Starter
Newbie
Joined: Apr 2004
Posts: 12
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From: Seattle, WA
'94 S600 (C140), '06 R350 (W251), '76, '77 & 79 Lincoln Continental Town Coupe
420 Check Engine Light
I have an '88 420 SEL which has its check engine light on. I am pretty mechanically inclined, but this was beyond me, so I took it to my mechanic (in indy) who took a lot of time to thoroughly check it out. Nothing. He even called the local Benz dealer who walked him through a checklist to make sure he had it all covered. Nothing. Finally the Benz dealer instructed him to reset the light, which he did. Fast forward 3 months and light is back and still the car runs perfectly. Nothing noticeable. What I am wondering now, is does anyone know how to reset the codes, or do I have to take it to someone with a special scanner/diagnostic tool? Words of advice are always appreciated.
Super Member
Joined: Jun 2003
Posts: 595
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From: Middlefield, CT
1994 E320
Older Bosch injection systems use a pulse readout system for interrogation of fault codes. All you need is an LED, some alligator clips, and banana jacks. The fault codes and diagnostic terminal are specific to the injection system. I only have the data for KE III (on my W124 260E). Someone else on the forum might have the 126 service literature, and can provide such info.
Thread Starter
Newbie
Joined: Apr 2004
Posts: 12
Likes: 0
From: Seattle, WA
'94 S600 (C140), '06 R350 (W251), '76, '77 & 79 Lincoln Continental Town Coupe
Jer,
Thanks for the info. I have all those tools you mentioned, but I don't know where to connect to get the codes. Also, how do I reset the check engine light? Thanks again for your help so far.
Thanks for the info. I have all those tools you mentioned, but I don't know where to connect to get the codes. Also, how do I reset the check engine light? Thanks again for your help so far.
Super Member
Joined: Jun 2003
Posts: 595
Likes: 0
From: Middlefield, CT
1994 E320
Look on the driver side wheel well for a black, round socket. This is X11, and is used to read fault codes and lambda output.
I don't know which pins are for data. I hope someone who knows will come along and post!
You reset the Chk. Eng. light by erasing each fault code. Fault memory is erased by displaying a code and grounding the data pin for 6-8 seconds. Then you move on to the next code until all are clear (LED on steady).
I don't know which pins are for data. I hope someone who knows will come along and post!
You reset the Chk. Eng. light by erasing each fault code. Fault memory is erased by displaying a code and grounding the data pin for 6-8 seconds. Then you move on to the next code until all are clear (LED on steady).
