original boost gauge not working

Hey All,

I need a hand. I've got a manual 1985 Silvia S12 CA18ET.... My boost gauge on the dash is not registering anything, the needle continuously on -7......in the 6000 posts I've read, all point to fitting an aftermarket boost gauge, something I can't do as I want to keep this car completely original.

Does anyone know the steps I should take in order to try to check out where the fault lies? I've checked and replaced any damaged vacuum hoses but still nothing. Does the boost sensor fail? Is there something wrong with the actual boost gauge in the cluster? Should I just leave it alone coz it's not worth it?

Any help would be much appreciated

Do you have a factory shop manual, if you don't have one you can still download one in one of our postings here:

https://club-s12.org/forum/index.php?topic=17058.0

You can find the testing for the boost sensor on EL85 from this PDF:

http://www.yariksteel.ru/manual/s12/s12_manual.pdf

Thank you for replying.......I do have one but as on EL86 I don't have a pressure pump gauge so I'm unable to test that way......and with the whole planet being on lockdown I can't get my hands on one.....does the boost gauge on the dash itself usually go or is the problem likely to be elsewhere?

Just use something to pull a vacuum or push some pressure and see if there's a voltage; use a shop vac perhaps?  Another thing to check for is a plugged vacuum line.  To check if the gauge is working you can put a small voltage and see if the needle moves.  Mine was working so I never have to trouble shoot.

Top man Bossman, thank you, I'll give that a try