Confussed !!!!

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Jun 30, 2011 | 07:38 AM

Tonyyak

Thread Starter

3rd Gear

Joined: Jun 2011

Posts: 3

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Confussed !!!!

For a while my service light would come on 10 minutes after I hit highway speed. I just had the stock radio replaced with an aftermarket and the light is gone. In fact when I scan the computer nothing happensI don't get the normal 1-2 or even the service light when I start it up. Any suggestions ?? BTW, it's a 90 L-98 coupe.

Jun 30, 2011 | 07:52 AM

bac22

Le Mans Master

Joined: Feb 2000

Posts: 9,060

Likes: 214

From: Epping NH

Do you want the Service Light back? I would think not having the Service Light on and no computer codes to be a good thing

.

When the after market system was installed they most likely disconnected the battery cable which I believe clears some diagnostic codes in the ECM. I would drive the car and wait to see if they return later.

What codes were you getting when you had the service light on?

Jun 30, 2011 | 08:46 AM

RetiredSFC 97

Team Owner

Joined: Jan 2009

Posts: 73,568

Likes: 33

From: Somewhere in Mo

St. Jude Donor '09-'10, '14

If your service light came on 10 minutes after highway speeds it was most likely your EGR needs clean and/or replaced. ( I have first hand experience with this)

As stated above, the removal of the batt cable cleared it for now.

Jun 30, 2011 | 09:30 AM

Kmcoldcars

Melting Slicks

Joined: Jan 2009

Posts: 3,181

Likes: 286

From: Puyallup Washington

Hey guys, I believe you have missed something. When he scans the codes (I am assuming with the paperclip method) he does not get the code 12 which should flash 3 times before showing any set codes and then 3 times to show all the codes have been displayed. Also, when he starts the car the service engine soon light should come on for a couple of seconds to show it is working.
I do not know the cause but I would think you should delve into the cause of why no service engine soon light and no codes 12 flashing.

Jun 30, 2011 | 09:52 AM

Tonyyak

Thread Starter

3rd Gear

Joined: Jun 2011

Posts: 3

Likes: 0

I did drive it for a while, in fact it is 35 miles from point a to point b. And as for the light not coming on at all. YES it's a good thing. And as for the light coming on for about 10 seconds, it doen't happen, in fact I don't even get the light when I go to start the car. For the code, it's either the EGR or the ECM, off the top of my head I don't remember the number.. Thx Guys

Jun 30, 2011 | 10:00 AM

RollaMo-LT4

Race Director

Joined: Oct 2005

Posts: 11,770

Likes: 175

From: Rolla Missouri

2021 C4 of the Year - Unmodified Finalist

St. Jude Donor '10 thru '25

Quote:

Originally Posted by Kmcoldcars

Hey guys, I believe you have missed something. When he scans the codes (I am assuming with the paperclip method) he does not get the code 12 which should flash 3 times before showing any set codes and then 3 times to show all the codes have been displayed. Also, when he starts the car the service engine soon light should come on for a couple of seconds to show it is working.
I do not know the cause but I would think you should delve into the cause of why no service engine soon light and no codes 12 flashing.

The fact that he gets no light at all now, means something happened during the sound system install.
As stated, that light should come on when you turn the key and then go out after the self test.

Just because he has no "Service Light" now, does not mean the codes went away.

Jun 30, 2011 | 10:11 AM

F22

Le Mans Master

Joined: Oct 2006

Posts: 6,842

Likes: 285

From: Palmdale CA

Let me add this: the 87' will have the SES (Service Engine Soon) light will come on intermittently during driving. Sometimes not at all for weeks. Ran the codes twice and all I got was the 'Hello' Code 12 and nothing else! Those OBD1 systems on the early C4's were pretty primitive and it doesn't surprise me.