Turbo Boost Lights on Digital Dash

86GNER

New Member
Joined
Jan 9, 2007
The digital dash cars have two lights on the dash that light up when the turbo is operating. However, only the bottom yellow light lights up when I accelerate. Besides being a possibly burned out bulb, does anyone know why the top light (I believe it is red) does not come on no matter how hard I mash on the pedal? Your help would be appreciated.
 
Probably the Hobbs switch on the passenger fenderwell. It has two wires on a connector in the shape of an L. There is an unused MAP sensor plug in the same harness.
Hope this helps
Bryan
 
There is an adjustment on the aforementioned switch. I think you can check the operation of each light by grounding each wire that connects to the switch. Your red bulb might be baked.

Jim
 
The top light should come on first, so if your bottom one is working it may just be a bulb like you stated.
 
An easy KEY ON test would be to take a 3 foot stripped wire and connect one end to the NEGATIVE terminal of the battery, the other end gets placed in each connector slot with it removed from the switch with the vacuum line on it.

If both lamps light, KEY ON TEST, when you ground each wire in the plug, (test one at a time it's easier), it isn't the bulbs.

If it doesn't light it's in the switch adjustment most likely, or possibly the wiring/connections back to the dash which is less likely.
 
Thanks for the info. Come to think of it, the top light (Low pressure yellow light) comes on. Its the red high pressure bulb that does not come on. Which way should I turn the high pressure adjustment screw to have the light turn on at a lower pressure?
 
Is it possible to get a high boost light if the low boost light does not come on (and is not the result of a burned out bulb)?
 
Yes it is possible to get lo or hi only on the dash.

Burned out bulb, bad wiring or connections to the dash location, or a bad switch adjustment or contact internally can cause that problem on either lamp circuit.

Unhook the wiring from the switch, and do the ground wire test key on car doesn't have to run to try the wiring to the lamps and dash to see if both bulbs are good.

Easy test to do. :)
 
An easy KEY ON test would be to take a 3 foot stripped wire and connect one end to the NEGATIVE terminal of the battery, the other end gets placed in each connector slot with it removed from the switch with the vacuum line on it.

If both lamps light, KEY ON TEST, when you ground each wire in the plug, (test one at a time it's easier), it isn't the bulbs.

If it doesn't light it's in the switch adjustment most likely, or possibly the wiring/connections back to the dash which is less likely.

I know this is an old one but I'm glad I found this post because I was about to pull the dash and replace the boost bulbs. I did the above ground test and both bulbs work. Checked the hose running to the switch, looks good.

Any thoughts on how I should start adjusting the switch or, should I just try and find a new switch? 21 years old, the switch could be trashed right?
 
I test mine with compressed air on a small regulator that gives me easy and quick adjustments from 0-15 psi. pressure with a hose on the sensor.

I first clean it out thoroughly with electronics contact cleaner.

I then use an ohm meter from the output terminals to the case of the unit.

Adjust the air and watch for the switch to close on the meter and at what pressure.

Cleaning the bracket with scotchbrite could help if it's not grounding to the car at all.

A good used one might be available from G-body parts.

Not sure if anyone has them new OEM or aftermarket.
 
Sometimes turning the adjusting screws in and out will allow the thing to work consistently again as well, but the final settings will have to be done on the bench with a good accurate air and gauge supply via a hose.

Find the two adjusting screw points first.
 
Dont even bother screwing around with the old part. GBodyParts.com Online stocks the discontinued GM part.

I had the same problem. I brought my replacement from NOS4GN. Do a search for on their site for "boost" and it'll come up.

By the way the low boost light comes on around 3-5lbs and the high boost around 10-12lbs. These settings can be adjusted somewhat by the screws, but it aint worth the trouble IMO. Just go by your boost gauge.
 
For $56 plus shipping I most definately would spend an hour adjusting and cleaning one before buying a new one, worth the trouble to me if it's simply a bit of oxidation from non-use.
 
Thanks everybody! I didn't even think they would be available anywhere.

I'll give it a little cleaning tonight and if it doesn't work I'll just grab a new one. $55 is definitely worth a little cleaning effort first though :)
 
Which way should I turn the....adjustment screw to have the light turn on at a lower pressure?

Didn't see this answered anywhere, but would like to know what turning the screw clockwise and/or counterclockwise does to the adjustment settings. Anyone know?
 
Didn't see this answered anywhere, but would like to know what turning the screw clockwise and/or counterclockwise does to the adjustment settings. Anyone know?

It adjusts the boost level at which the lights are triggered.
 
It adjusts the boost level at which the lights are triggered.

Yes, but what I am looking for is what happens if you turn the screw clockwise or counterclockwise. Which direction raises and which direction lowers the boost level that the lights are triggered?
 
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