Fault Code Confusion

[deanyel]

Car is a 1992 400E. The Check Engine light is on. The engine stumbles when it's warm. I have found a 8 pole diagnostic connector with a button and LED light. This gives me a code 7, which may be "Ignition System Faulty" if I'm looking at the right list of codes. This would be consistent with the performance symptoms.

But next to the 8 pole connector is what appears to be the round 38 pin Diagnostic Connector - I can't be sure because I can't seem to get the cap off of it.

So what's the difference between the 8 pole connector and the 38 pin connector? And what does it take to get the cap off the round one?

[moruzzi]

I have a 92 400E as well (mine doesnt have the button and light, I believe it was only required in CA).

Anyway, the 38 pin connector is under the cover of the computer box. The box where a battery would normally be - there should be pne round cover about 2 in in dia. Use the appropriately sized socket to remove (its a 1/4 turn like a gas cap) and there's the 38 pin in all its glory. Alternatly you can remove the entire cover - 4 allen head bolts.

I think the cover you are refering to is the connector for the electronic throtle actuator. Its about the right size and is in that area.

You will need to build a code reader to get the code pulses from the 38 pin socket. This is covered in a variety of places (do a search) including my favorite
http://pages.prodigy.net/jforgione/MB_S500.html

He is a member and posts regularly.

Paul

[stevebfl]

When you are using the 8 pin connector I think there is only the DM (diagnostic module) is available there.

if the DM tells you that there is a ignition failure you will want to inquire on the DI module, pin 17 in the 38 pin connector.

[JimF]

it's sounds like the good ol- "ETA" is bad. But you need to pull codes to be sure from the EA, pin 7 to see what DTCs are stored. I would also check the LH module, pin 4 and ASR, ABS on pin 6.

Check my page (click on the 'www' icon below) and check out Menu #24. You see some representative codes when my ETA went bad.

[deanyel]

I found the 38 pin - take off the computer box cover it sticks out like a sore thumb. The other round plug wires head off under the air filter housing so it probably does go to the ETA. On the eight pole connector, I was not aware that it was a CA model but it's possible as I am in AZ. I plan to build a code reader but probably not for a few days. Jim, I had already been to your site - that's how I figured out what a code 7 was. I do suspect ETA at this point. Thanks to all.