Boost/Tach Bar Graph Gauge

[TurboTJT]

My Boost/Tach Bar Graph Gauge is maxed out at idle.
What are the potential causes?
More importantly, what is the fix?

 

[RegalT-type85]

- CEI - Casper's Electronics, Inc. If you still want them send them here to get repaired. These are 2 gauges that always go out. Most of us get aftermarket gauges.

 

[Red Regal T]

I have the same condition. Seems like the signal shorted somehow. Like if I ground my fuel gauge sender wire, it always reads over past full. Hate to pay $100 to fix something that ain't necessarily broke.

I'm sure no one uses these gauges for anything other than they are part of the GN package.

 

[RegalT-type85]

I have mine installed still, FULL TACH all the time. I have a aftermarket boost gauge. when i put LEDs in my dash, i took out the TACH/BOOST gauge.

Played with it a bit, the contacts on the back if you ground the right one it goes back to 0 and will read right. I had to hold it in place and kept blowing a fuse(smartglows) i stopped after 4 fuses blew haha. I think if i were to take it out, spend some time with it, i could figure it out. Just throwing that out there. I dont remeber what contact inner, if you look at it there is alot of crap in that one gauge haha.

Maybe i will take a multi reader and try to fix it again, why not right. Don't wait up tho

If i do find how to, i will post it for free to all.:wink:

 

[GNVenom]

I doubt if you'll find the problem It's a genetic defect. Here is some reading if you're interested. This will explain:

http://www.installationinstructions.com/FYI/tachboost.pdf

 

[Red Regal T]

I doubt if you'll find the problem It's a genetic defect. Here is some reading if you're interested. This will explain:

http://www.installationinstructions.com/FYI/tachboost.pdf

Thanks for that, John. Actually I thought your price for a refurbished unit was more than fair. I just wasn't sure if it wasn't something stupid like a grounded wire. I'll add a replacement unit from you to my list of things to buy. :biggrin:

 

[TurboTJT]

I doubt if you'll find the problem It's a genetic defect. Here is some reading if you're interested. This will explain:

http://www.installationinstructions.com/FYI/tachboost.pdf

Thanks John. I've got 1 down, my other 5 TRs are still working for now.
Sounds like all turbo tach/boost modules are like candles in the wind.

 

[GNRick]

I doubt if you'll find the problem It's a genetic defect. Here is some reading if you're interested. This will explain:

http://www.installationinstructions.com/FYI/tachboost.pdf

John- I got lost after "technical information". Is the test/calibration equipment portable, and if so, can you repair our gauges at Bowling Green in October? Maybe you could do it in your booth, or your hotel room? :biggrin:

 

[GNVenom]

Actually it's a bit complicated to do it in the field. I use a frequency generator for the tach, and a precision resistor for the boost...then I use a diamond point to "grind" the resistance pad into calibration. The factory used a laser to cut the resistor pad, and I believe that's the reason they all fail. The laser creates a plasma blast at the cut line, causing "whiskers" to form over time. It's the whiskers that grow, and eventually cause the failure.

When I use the diamond point, there is no heat stress. Then I coat the calibrated resistor (they didn't coat the pads from the factory - which led to atmospheric exposure and ultimately failure). So coating it seals out the air and you won't ever have a problem after that.

Hope this makes sense.

 

[Bruce Urie]

John, I'm so impressed with the procedures you use to repair these boards. That shows some serious research/developement in coming up with this repair procedure. You really dug deep into the design of this system and I extend my admiration to you for doing so. Being a retired mechanical engineer, I understand your well thought out system to overcome the common design defect on this board from GM. Well done, John. You really know your stuff. Of course, when my gauge goes out, I will definately send it to you as you have shown you know what you're doing. Your repair price is well in line with what you have to do to fix this situation. I just really admire folks who accomplish so much from knowledge and research. So, I had to extend that admiration to you. I was just blown away with your explaination. Many, many people are not aware of the "whiskers" you speak of. I have seen it in my line of experience in engineering over the years. I'm glad you brought it to the forefront. Thanks for your clear explaination. You really are a positve asset to this forum. I, personally, wish you decades of sucess. You are quite the knowledgable one.

Hope I didn't swell your head to the bursting point.:tongue:

Bruce '87 Grand National

 

[TheGovernment]

how much is it to get the gauges fixed? I have 2. One that the tach and boost work fine but the housing is all beat up and the one thats in the car is really good shape but the tach is stuck at 2000 rpm and goes up from there. Is there a way to switch the tach module over for the crappy one to the good one? or do I just send in the good one to get fixed and plug in the crappy one until I get it back?

thanks.

 

[Heg87t]

Check This Out

My Boost/Tach Bar Graph Gauge is maxed out at idle.
What are the potential causes?
More importantly, what is the fix?

Are the tack lead and fuel pum prime leads near the alternator connected?
They are not supposed to be but GM put connectors on them that mate and look like they should connect. I think if you connect them it will mess with your dash tach.

 

[Red Regal T]

how much is it to get the gauges fixed? I have 2. One that the tach and boost work fine but the housing is all beat up and the one thats in the car is really good shape but the tach is stuck at 2000 rpm and goes up from there. Is there a way to switch the tach module over for the crappy one to the good one? or do I just send in the good one to get fixed and plug in the crappy one until I get it back?

thanks.

CEI - Casper's Electronics, Inc.

 

[TheGovernment]

Ahhh, so you can just swap them out. sweet, I think I'd still rather send mine in and get a fixed working one rather than switching to another old one.

thanks!