Stock Boost Gage

[Johnboy]

I was wondering if anybody has a schematic or a description on the stock boost gage for the TTA. Mine is not working and would like to get it working again.

Thanx

 

[WARBIRD1989]

Check the vaccum line to the black box {map} looking thing on the top on the heater blower, this box tells the gage what to do.

 

[Razor]

Test the 3 bar sensor,

The green wire should read 1.5volts DC ignition on, on the sensor as indicated above.

Another test, if you unplug and jump the green to gray wire on the plug, the guage should go past 20 PSI. Have someone watch the guage when you do this. And be quick to see if it responds. A paper clip can be used.

 

[Johnboy]

BOOST GAUGE

Thank You

Checked the connectors and found a jumper in-line with the Bar sensor and the wires were reversed. Not sure why that was in there. Anyway I have 1.585 V on the green wire now. Shorting the green to gray does not cause the gauge to move though. Looks like my gauge is toast. Anybody ever have any luck repairing the gauge??

 

[Johnboy]

Stock Boost Gauge

I thought I would just reply on this thread and explain what I found and how I fixed it incase anybody wants to fix their inaccurate gage or tries a search on this as there is not much on it.

Here is what I found.

The boost gauge is hooked up separately on back of the instrument cluster and it was disconnected when I pulled the cluster out. After hooking it back up the gage was found to be off almost 10 PSI, hence the reason someone must have disconnected it. Anyway what I did was set my air compressor to 10 PSI and then hooked up another test pressure gage on the end of the air hose to verify regulator gage was correct. After doing that I hooked up the hose to the MAP input with ignition on. I then carefully removed the gage pointer and re-inserted at the set pressure of 10 PSI. After doing that I did a three point check (2,10,18 psi) to verify reading was correct and all is well now.

Anyway I thought this might help someone if they want to get more accurate on their boost gage. This might not work in all cases, but did on my car.

 

[Razor]

The TTA MAP is wired backwards from all other GM MAP sensors. In the 90's GM decided to make the MAP uniform and if you go to GMpartsdirect.com and try and get a 3 bar, it will tell you a plug is needed. What that plug does is reverse the wiring on the MAP making it then uniform with the other map sensors GM makes.

Why did they wire the original MAPs backwards??? Dunno. Probably has to do with the resistor placed in the harness leading to the MAP that drops its 5volts supply to 4.7volts zero'ing out the dash guage.

I have never looked at one of these guages, would be suprissed if one were really bad. But anything is possible.