RWD 19xx-1984 DeVille and Fleetwood, 1985-1996 Fleetwood and Brougham ForumForum for discussions regarding the rear wheel drive Pre80s-1984 DeVille and Fleetwood, 1985-1996 Fleetwood/Brougham.
I have a 1993 Fleetwood Brougham powered by the LO-5 5.7 liter with 139 000 miles & I keep getting a Service Engine Soon light at 60 mph. When I went to the shop to pull the code they found nothing?? The worst part is the light only will come on at 60 mph or more....but is gone when I restart the car? Went two times to GM and same thing "nothing to report" Might be the EGR but it looks clean & not very old. Please help.
Try this, drive the car in 3rd gear, not 4th at 60 MPH. I'm thinking the computer is seeing an issue with overdrive and sets a code. Each and every time the computer sees the issue the light returns. Thats why no light upon restart. It must reach the RPM where the fault is. If no light in 3rd, its probably a trans related fault. Please get the fault codes and report back.
I'm going to guess DTC 32, EGR. There's no reason that code wouldn't be available to scan, though. Perhaps the shop you used has no way to check for codes (they think).
The way the EGR test works is, you must be fully warmed up, vehicle speed and engine load within a range and it must be steady enough for long enough for the ECM to perform the EGR test. What it does is monitors manifold pressure via the MAP sensor before and after commanding EGR operation. If manifold pressure doesn't increase by a predefined amount, the EGR is thought to be malfunctioning, and it sets a code.
Try this, drive the car in 3rd gear, not 4th at 60 MPH. I'm thinking the computer is seeing an issue with overdrive and sets a code. Each and every time the computer sees the issue the light returns. Thats why no light upon restart. It must reach the RPM where the fault is. If no light in 3rd, its probably a trans related fault. Please get the fault codes and report back.
This reminds me of when my 83' Deville ws new, the service soon light would come on above 60 mph for the 1st 1000 miles, the so called "break in" miles, after 1000 miles it went out, but I recall keeping the car in 3rd gear & not going over 55 MPH.
it's most likely nothing, maybe the switch shorted out, or for some odd reason the car is seeing the miles @ less than 1000. Did the odometer recently turn over? did you lose power? did u replace the Dash module or do any work in the dash board?
No to all of the above. But the car dose have over 139 000 miles it. Went back to GM & still no INFO TO REPORT from the scan.....but the GM tec did note that the EGR was a jobber part. Would this matter?
This reminds me of when my 83' Deville ws new, the service soon light would come on above 60 mph for the 1st 1000 miles, the so called "break in" miles, after 1000 miles it went out, but I recall keeping the car in 3rd gear & not going over 55 MPH.
it's most likely nothing, maybe the switch shorted out, or for some odd reason the car is seeing the miles @ less than 1000. Did the odometer recently turn over? did you lose power? did u replace the Dash module or do any work in the dash board?
I highly doubt that was what was happening. The ECM has no idea what the vehicle mileage is, especially in 1983. The ECM also didn't control the transmission (except for the lockup torque converter), though I am not sure if you said you kept it in 3rd, or the car did. I bet it was a coincidence.
I highly doubt that was what was happening. The ECM has no idea what the vehicle mileage is, especially in 1983. The ECM also didn't control the transmission (except for the lockup torque converter), though I am not sure if you said you kept it in 3rd, or the car did. I bet it was a coincidence.
I kept in 3rd gear, & there was a page dedicated to the service soon light coming on @ over 55 in the break in section of the Manual, thats how we knew it wasn't a prolbem.
I was just throwing somthing out there,
these transmissons aren't electronic so what else could make the light illuminate.
Your car is 15 years old, it might be a good idea to dis-connect and clean wiring harnesses and electrical connectors under the hood. If corrosion builds up, electrical signals can't get through and do their job.
