Digital Dash turbo boost reading went out...

SHEPP2

Member
Joined
Oct 28, 2008
I have a 87 GN with a digital dash. The turbo boost reading was working fine but just went out or just stop lighting up. Everything else on the dash works fine. Only the the top light (yellow/orange) would come on never the bottom which is red I think from what I have read. :confused: Any help would be greatly appreciated...
 
I have a 87 GN with a digital dash. The turbo boost reading was working fine but just went out or just stop lighting up. Everything else on the dash works fine. Only the the top light (yellow/orange) would come on never the bottom which is red I think from what I have read. :confused: Any help would be greatly appreciated...
6 years and not ONE reply to this problem??
Or, is it that I'm not using this site correctly?
I have the exact same issue that just arose, looking for a solution.
 
I have an '86 GN with a digital dash as well. Unfortunately all I can say is, there is a map sensor/ boost switch on the passenger inner fender that triggers the boost lights.
I've had my dash apart for other light bulb replacement, but I don't recall if there are regular light bulbs in the boost lights as well.
Install a boost gauge if not done already. When I installed a boost gauge in mine the summer of '86 I noticed the amber light came on at 2 psi boost and the red light came on at 5 psi boost, it's not something that should be looked at anyway especially now that we have the knowledge to safely run more than twice the stock boost levels.

If it is the dash, Caspers Electronics has a rebuild/ repair service.
Sorry I can't be of more help.
 
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On mine, it was the Hobbs switch. It is mounted to the passenger fender. It has a vacuum line and electrical connector attached to it. They tend to go bad over the years and stop closing to ground when pressure is applied like they're supposed to. Part is no longer available.

If you do a search for "Hobbs switch, you may find some threads about it.


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Ground the two wires that come out of the connector on the MAP switch on the passenger fendwall. Turn the IGN Key to ON and see if the two lamps light up on the dash.

If so clean the mounting bracket to fenderwall mount as that supplies the ground to trigger the lights.

The switch can be removed and cleaned with electronic cleaner there are two adjustable mechanical switches inside that can be set and checked with regulated shop air and an ohmeter. One lead to the case and one to each output tab. There are two screws under rubber covers for adjustment.

Also use a gauge and make sure you have boost pressure to the MAP switch itself on that hose.

20170806_113403.jpg
 
I have an '86 GN with a digital dash as well. Unfortunately all I can say is, there is a map sensor/ boost switch on the passenger inner fender that triggers the boost lights.
I've had my dash apart for other light bulb replacement, but I don't recall if there are regular light bulbs in the boost lights as well.
Install a boost gauge if not done already. When I installed a boost gauge in mine the summer of '86 I noticed the amber light came on at 2 psi boost and the red light came on at 5 psi boost, it's not something that should be looked at anyway especially now that we have the knowledge to safely run more than twice the stock boost levels.

If it is the dash, Caspers Electronics has a rebuild/ repair service.
Sorry I can't be of more help.
Hi,
I found the issue as being a poor ground connection at the pressure switch located on the passenger side fender under the hood.
I suppose it works by activating a diaphragm when under vacuum, similar to the old style water pressure switches in old style washing machines.
How's your 86 holding up?
My next project is to install the scan master tool, I just installed a M.A.F. & Translator as the original one finally crapped out on me.
 
Ground the two wires that come out of the connector on the MAP switch on the passenger fendwall. Turn the IGN Key to ON and see if the two lamps light up on the dash.

If so clean the mounting bracket to fenderwall mount as that supplies the ground to trigger the lights.

The switch can be removed and cleaned with electronic cleaner there are two adjustable mechanical switches inside that can be set and checked with regulated shop air and an ohmeter. One lead to the case and one to each output tab. There are two screws under rubber covers for adjustment.

Also use a gauge and make sure you have boost pressure to the MAP switch itself on that hose.

View attachment 307357
THANK YOU!!!
That's what is was..A bad ground.. The mounting screw was loose.
I could probably use an old whirlpool washer water level pressure switch ( as crazy as it sounds) if this ever goes bad. After all, it's only completing a circuit and the washer part works in the same manner and is adjustable.
 
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