Service engine soon light

[harvey85]

To explain, all the vacuum lines on my electric quadrajet had no hoses. As I tried to figure which ones needed to be plugged and connected, I had put my finger over the manifold pressure tee a couple of times and I assume this is what gave me the service engine soon light. Strange thing though after I got the vacuum lines plugged and the distributor vacuum advance hooked up, I still had the engine light on and my voltmeter was pegged left about 9 oclock and oil pressure pegged past 60. Any help as to what could be the cause would be nice. Still trying to find the ALDL switch to see if I can figure out what the code is, but the gages are really throwing me for a loop. Truck runs fine, use it as a daily driver and have had no issues driving with the service engine light on.

[TwinTurbo]

If it annoys you, take out the bulb and send me the lens I need it LOL

[Sodell]

What year, you need to check the codes.

[harvey85]

It's an 1985, 305. I would love to check the code but I just spent the better part of 30 minutes looking all under and around the dash and found nothing that looks like the aldl port out of the Haynes manual

[Sodell]

I think you have obd1..you can check it with a paperclip...try this. It's probably the best explanation I have found

http://www.theimportkiller.com/forum...hp?topic=420.0

[harvey85]

I think I am just going to take a hammer to it until the light goes away, looked everywhere and can't find the connector. Really just want to know why my gages are pegged out.

[Sodell]

Originally Posted by harvey85

I think I am just going to take a hammer to it until the light goes away, looked everywhere and can't find the connector. Really just want to know why my gages are pegged out.

We have all been there...

[hatzie]

Which gauges are pegged?
The ALDL port should be somewhere near the steering column under the edge of the dash sheet metal.

[harvey85]

The voltmeter is at 9 o'clock oil gage about 2 o'clock the coolant temp is reading high, close to the red after warming up and I filled up about three days ago and the fuel gage is still reading full. I know vacuum advance is supposed to help fuel economy but I doubt it would make that big a change
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[mtnsackett]

I'm not sure about the Voltage gauge being spiked but on my 85 if the Oil pressure sending unit wire comes un plugged it pegs at the top of the gauge, maybe you unhooked something with out realizing it.

[harvey85]

so I'm pretty sure I have a ground somewhere, filled up today and the gas gage went to the 4 o'clock position. Now I just need to figure out how to trace down the ground

[Shyguy]

Disconnect the battery for about an hour and see what happens when you hook the battery back up and starts the engine.

[hatzie]

Your gauges are analog meters. The ECU is for spark knock control and maybe some coarse fuel mixture control it doesn't run the gauges.

Volt gauge at 9:00 0VDC = No power or no Ground at the cluster plug damaged flexible printed circuit or a bad volt gauge.

Oil gauge at 2:00 (pegged) usually means you've inadvertently unplugged the sender wire, the wire is cut, or the sender has failed. If you ground the oil pressure sender wire it should read 0 PSI.

Temp gauge sounds like it's got a failing sender or the wrong sender was installed sometime in the last 28 years. If the temp sender wire is partially grounding on the exhaust manifold or somewhere else you could get a nailed temp gauge too.

Assuming that the fuel gauge does move and eventually reads E when you're close to empty... The fuel gauge sender is engineered to read near full for almost 3/8 of a tank... GM did this with all their cars and trucks after early 1974. I have the '70s Chevrolet Service News with an article that outlines this change. This is why a "normal gauge" reads close to full for quite a while and then drops relatively fast after it starts to move. All of the "Big 3" did this.