I have a malfunctioning stock boost gage that reads sometimes while driving. The next time I took the car out it was not moving at all. Where does the singal come from, the boost sensor? Just wondering where I should start checking. Oh yeah, the car does seem to still have strong boost too so I am guessing it is only a gage problem but then again I may be out to lunch.
Thanks

 

that **** is useless anyway

 

Heh yea, depends on your luck, sometimes they work sometimes they don't. I would look into a digital boost controller if you dont already have one. Or just buy a aftermarket boost guage.

 

The signal comes off the boost sensors connector. Its the brown/red wire. The brown/red wire leave the sensor and splits off in two directions. One wire goes to pin 2B of the ECU and the other goes to a connector b/t the EMISSIONS harness and the FRONT harness. It's name is X-15 and is located above and in front of the passengers feet From there it leaves X-15 on a BLUE/WHITE wire and goes to plug CO-3, which is a connector b/t the combination meter harness and the FRONT harness. From there it goes to connector CO-2 on the combination meter.

By the way, there is also a ground wire that is at issue. The boost gauge needs a ground. It leaves the combination meter on a Black/White wire and goes to CO-3 where it interfaces with the FRONT harness on a Black/Blue wire. That's as far as I care to go.

There are free downloads on the internet of the wiring diagrams. Download it and you can see how things work.

NZConvertible would now tell you that you NEED to find out why the gauge is intermittent. It's possible that it's more than the gauge that is at fault. You NEED to have the pin 2B see the output of the boost sensor. Right now you have no idea if the ECU is/is not seeing the signal. It could be coming and going just like the gauge is . You need to find out if 2B is seeing the signal. The gauge is insignificant as far as it working/not working. The ECU MUST see the output of the boost sensor. Done.

 

Yea umm just buy aftermarket.

 

Hailers, thanks for the detailed info.
I did a search on the net for electrical prints but could not find the site. Anyone have a link to get there?
Have voltmeter...Will test!
Thanks

 

When I installed my S-AFC I did some pressure signal testing.
The pressure sensor seems to be very reliable.
The voltage at 2B on the ECU was always there.
The weakest link appears to be the dash gauge connections.

 

Okay, can you confirm you're actually boosting?
Do you have an aftermarket boost gauge installed?
How do you confirm the turbo is boosting if you don't have an aftermarket boost gauge?

The stock boost gauge has a self-test everytime you key ON before you crank the starter.
Do you check this everytime before you start the engine?
The needle is supposed to "jump to 0".


-Ted

 

A little background,
I just bought an 88TII AE (brought her home on saturday). Have only driven it 4 times and never had a boost gage prob. My friend takes it out and it does not work? This morning i put the key in the switch and the needle bounces up to "0" so it appears to be functional now. I will try and drive it again (keeping an on on that needle when i start the car) and see what happens.
I will be putting on an aftermarket boost gage soon but considering I just got the car and it is almost snowing here it will be next year until I finally get that on the go.

 

You're not alone.
My dash gauge works about 80% of the time.
It was worse until I cleaned the connector pins on the dash harness plug.
Even when it's low or dead, the S-AFC's pressure sensor tap on the ECU is still good.

 

my boost gauge on all my t2's crapped out... one t2 kinda worked but the ecu always got a signal... I think it's the cluster... I've had more problems with clusters than people have with vacuum leaks.

 

This morning I took a closer look at my problem. I put the key inthe ignition and swtiched it at least 20 times. The boost gage bounced to almost "0" on 15 occassions the other times it did not move. From that it appears at least that I have a dash signal problem. Looks like i better buy an aftermarket boost gage sooner then later.