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SL-Class (R129) 1990-2002: SL 280, SL 300, SL 320, SL 500, SL 600, SL 60 AMG

SL/R129: Diagnostic plug

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Old Feb 23, 2021 | 01:46 PM
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Dale1941
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From: Vancouver, Canada
1993 500SL 2002 Holden Maloo Ute
Diagnostic plug
Hi all. On my '93 500SL there is a problem with Diagnostics. When I first imported the car to Canada, it had to have a fairly comprehensive safety check. Prior to the safety check, it had a code, which I managed to clear. When the tester took the car on road test, he went to an "expert" to check the codes. Since that time the plug is inoperative, so don't know what the "expert" did. It has both the positive and ground feeds, but using the home made blink bulb tester, which previously worked, it has no response. Any thoughts on where I should look ? Thanks.
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Old Feb 24, 2021 | 04:47 AM
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R129.067 (500SL '93), EQE, MGB
Dale1941, start by verifying that your diagnostic port has +12V (ignition on) and chassis ground. In the 38-pin OBD1 socket they are pins 3 and 1 respectively. In case you have the older 16-pin socket, terminals 16 & 1.
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Old Feb 24, 2021 | 12:57 PM
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Dale1941
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1993 500SL 2002 Holden Maloo Ute
Yes, these pins are connected. (38 pin connector)
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Old Feb 24, 2021 | 01:01 PM
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Dale1941
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Don't know what the acronyms mean.
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Old Feb 24, 2021 | 02:20 PM
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R129.067 (500SL '93), EQE, MGB
So your tester's LED is lit but you get no blinks from any of the test connector pins - right?? Try give us some more clues.
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Old Feb 25, 2021 | 04:07 PM
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Dale1941
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1993 500SL 2002 Holden Maloo Ute
No, the LED doesn't light up. Don't really have more information to give.
Thanks for the responses.
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Old Feb 26, 2021 | 04:08 AM
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R129.067 (500SL '93), EQE, MGB
Well, if you have 12V and ground present in the diagnostic socket but no test light, the primary suspect must be your home made tester.
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Old Feb 26, 2021 | 07:19 PM
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Thanks Pazo. I guess I wasn't explicit enough in my last message. The LED lights up by pressing the momentary switch (red - black wires) ,but plugging in the yellow diagnostic wire does not give a blink code when the momentary switch is pressed.
Dale
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