VW Jetta LED Boost Gauge
VW Jetta TDI "In-Dash" 0 - 25 or 30 psi Boost Gauge
Before and especially after additional performance modifications have been completed and installed, it is imperative we know whether the Electronic Control Unit/Module (ECM/ECU) is providing the engine with enough fuel under high boost and/or load. You will want to know how much boost your turbo chargers are providing you with. For a start all the cash you spent on the ECU can be quantified if it lives up to the boost specs. Optionally, if you have gone the electronic boost controller route, you will want to see the boost information at eye level. Boost must be monitored closely when doing turbo upgrades and other inlet manifold pressure related performance modifications. Now, you can go and buy an "off the shelf" boost meter from your favorite after market parts store, and install it somewhere in the car where it is guaranteed to look like an "afterthought" and join the "Rice Rocket" & "Boy Racer" brigade (not my terminology). You could spend copious quantities of cash on an integrated system in your instrument cluster, or you can do a proper job, with the satisfaction that you did it all yourself. And hey, that is half the fun, isn't it?. We chose to build and design our own Integrated 1 - 25or 30 psi Boost Gauge integrated into the Tachometer of the stock instrument cluster. It uses either the car's stock MAP sensor readings (in this case we use an external sensor as the stock unit is limited to 20 psi) to give real time boost pressure readings on 20 1.8mm LEDs. LED number 1 is 1.250 for the 25 psi unit or 1.5 psi for the 30 psi unit. (25/20 or 30/20 respectively) and so on up to 25 or 30. It is accurate to +/- .250 psi when calibrated correctly. It can be easily adapted to read virtually any boost pressure, the only limitation is that of the selected pressure sensor. It can use any 5v pressure sensor. This article focuses on utilization of an external 3 Bar MAP sensor we purchased separately. The parts we provide are for sea level operation but can easily be calibrated for other altitudes. Our Boost Gauge integrates into the Dash (Check out this page for a kit of component parts or a complete unit) so it looked as if it was there from the factory. This takes a lot of planning and measuring, in the long run it will look perfectly acceptable to the most discriminating connoisseur.
Disclaimer (Please Read it Thoroughly)
By connecting and using this Custom Gauge you agree that the designer and author of this document and gauge is in no way responsible for damage to persons, a vehicle or vehicles as a result of installing meter.
Liabilities: The author and designer assume no responsibility for the modifications you do on your car. Although to our knowledge these instructions are accurate, this includes any errors that these instructions may contain, any differences between your car and the one(s) showcased, as well as any errors in following the instructions. If you don't feel comfortable working with automotive electrical wiring we suggest you let someone with some experience do these modifications. The installer should posses a good understanding of the electrical system of the vehicle being worked on. Please double check all your connections and ALWAYS work with the car battery DISCONNECTED. Always keep your safety and that of others as the highest priority.
Warranties: The modifications described in this document could potentially void any manufacturer's warranty you may have left on the car (not likely, but possible nonetheless). You assume all responsibility if your car is still covered by warranty.
Legalities: Laws in your country/state/region/whatever may not allow you to modify systems such as these on your car, the penalty being at least a fine. Please check with your local authorities to be on the safe side.
We also assume NO RESPONSIBILITIES what so ever for any accidents cause by the driver gazing at this tremendous addition to the stock instrument cluster while they should be concentrating on the road and their driving. We always endorse good and safe driving practices at all times. With that, good luck, and have fun with this Custom Made Gauge.
The first thing you need to do is acquire an electronic Boost Gauge as described in this article (And on this page). You will need to be reasonably proficient with a soldering iron and lead solder, as you will be using them a lot. (Or you could get someone else to do it)
Check Out The Video! Click Here Now!
This article is for the real "Do It Yourselfer", we designed and built our own Custom In-Dash Integrated Boost Gauge, and that is what this article covers.
Completed 25 PSI Stock Unit Installed in Vehicle - Click for In-Action Video
Completed 25 PSI Bora Unit Installed in Vehicle - Click for In-Action Video
Main Boost Control Unit
As you can see by the layout, there are quite a few components. The signal comes into the unit from the MAP sensor, we spliced into it directly on the sensor. Remember to DISCONNECT the BATTERY BEFORE beginning any electrical work on the vehicle. We simply tapped into the car's vacuum line at a suitable point. There are many of them, choose one that involves the least amount if vacuum pipe to be run from the external sensor. The sensor is not intended to be in the engine compartment, so locate it beh1nd the driver's side knee panel and run the vacuum pipe through the firewall into the engine compartment. You can run the pipe through the firewall access hole, it is huge and has plenty of room. It comes out behind the ECU in the rear engine compartment. Switched ignition power can be derived from the ECU main wiring loom. Or any convenient point at the car's fuse box.
The "Dimmer" wire needs to have +12v when in Dim Mode, and ground or floating when in Daytime or Bright Mode. This can be done in many ways. There is a Fuse in the fuse box that is marked "Headlight", you can tap +12v from here. Or, from under the dash you can take the dimmer wire from the power connector harness and splice it into the GREEN/RED or GREY wire on your headlight switch harness. This is the wire that activates the dimming circuit on the control unit when it receives a +12V signal from the parking or main light circuit.

25 Segment Boost Gauge Main Control Unit, Not To Scale
Please refer to the following layout diagram for all the interconnection and external wiring information.

25 Segment Boost Gauge Main Control Unit, Interconnection & Wiring Layout, Not To Scale
Installing The Boost Gauge in the Dash
This is the part we were quite concerned about doing, and a quick call to our friendly dealer and spotting some eBay Auctions, confirmed that to replace the dash was a relatively inexpensive option, reassuring us that the parts we were about to potentially destroy were available as replacement parts. Armed with this "insurance" we proceeded very cautiously. The following steps involve drilling and cutting the dash assembly. Unless you are pretty good mechanically, we recommend you simply read this for interests sake, and put a commercially available boost gauge somewhere in your car. If you do choose to remove the dash assembly for any reason, do not forget to DISCONNECT THE BATTERY.
Step 1 - Remove The Dash Complete With Gauges and Wiring
This is a very easy procedure. You can refer to the car's repair manual for details. We proceeded as follows:
Now that you have removed the dash assembly, the fun can begin.
Step 2 - Dismantle The Dash To Remove The Tach Dial
This is quite easy, you just need a few nifty little pieces of plastic or metal. We used 1/16" plastic sheet. We use a lot of this plastic sheet, where do we get it? you may ask. Well, you know those three ring binders you use all the time for files, at the front and rear there is usually a sheet of plastic, either white or black used to support the pages. That is what we use.
Step 3 - Measure, Mark up The Tach Dial and Prepare for Drilling LED Mounting Holes
This is the very tricky bit. It can be done a number of ways, this step describes how we went about doing it. We chose to locate our 20 Boost Gauge LEDs (1.8mm ) in the Tach dial. We made a semi-circle of LEDs between the stock Tachometer numbers and the indicator lamps. The measurement was not that easy. A template was created after many, many iterations and here is what it looks like. It includes the layout from another project (The Air Fuel Meter) we were installing, which is described in another article. You will need a ).070" high speed steel drill bit.

Tachometer Dial Drilling Template & Alloy Blanks
Here is what we did:
Dash Drilling Template, With Key Detail, Top & Bottom (Note Location Hole at 12:02 Position)
Step 4 - Drilling The Dash!
As we only had one chance to get this right, we checked and double checked our measurements, and then we checked them again. The drill we chose was a 0.070". of an inch. (a tick smaller than needed for 1.8mm LEDs), We used a drill press at 3000 - 2340 rpm.
As you will see in the photos that follow later in this article, it was a tight squeeze.

Stock Tachometer Dial, Drilled, Ready for Lttering to be Applied

European Bora Tachometer Dial, Drilled, Ready for Lttering to be Applied
The above photo shows all 20 1.8mm LED holes in a semi-circle for the Boost Gauge. As you can see it is a very tight fit. But we were really pleased with the out come. Now onto installing the LEDs and the electronics.
Step 5 - Installing the LEDs
This is the most time consuming of all the steps. It is not hard to do, just slow. As you can see in the above photo of the dial, we applied 12 point white dry transfers to the dial. You can choose your own numbers and letters, just be careful not to obscure the warning decals on the dial. The decals are clearly visible when you hold it up to the light.
You will need the following items:
Tachometer Dial, Drilled Showing Both Stock & Bora Dials, with Lettering Applied (25 Psi & 30 PSI Samples)
Here is how we installed the LEDs.

Tachometer Dial, Ready for Placement of Indicators
|
|
![]() |
![]() |
|
Preliminary Indicator Bonding Examples

Preliminary Indicator Bonding Completed and Left to Dry for at Least 5 Hours

Stock & Bora Tachometer Dials, with Different Indicator Color Combinations Installed
Step 6 - Wiring Up The LEDs
You can do this any way you wish. We used 28 swg stranded wire with a very thin insulation. You need as thin wire as you can get. 28swg is the thinnest we wanted to go and stranded wire is more flexible than solid, although there is no real reason that solid wire could not be used. We wired 20 LEDs one by one , starting with the closest to the exit point.
|
|
![]() |
Tachometer Dial, 20 LEDs Installed, Showing Part 1 of the Bonding Process
|
|
![]() |
![]() |
Tachometer Dial, 25 LEDs Installed, Showing Part 1 of the Bonding Process
|
|
The Weller Temperature Controlled Solder Station Ready to Go
|
|
![]() |
![]() |
Tachometer Dial Rear, 25 LED Wiring, Notice Very Close Fit Between the Markers
|
|
![]() |
![]() |
Tachometer Dial Rear, 25 LED Wiring, Tieing Down the Loom
|
|
![]() |
Tachometer Dial Rear, 25 LED Wiring, Ready for Part 2 of the Bonding Process, Notice Very Close Fit Between the Markers
|
|
![]() |
Tachometer Dial Rear, 25 LED Wiring, with Part 2 of the Bonding Process, Notice the Masking Tape Over the Markers
|
|
![]() |
![]() |
![]() |
Tachometer Dial Rear, 25 LED Wiring, Painted and Ready for Installation into the Cluster
|
|
![]() |
![]() |
Tachometer Dial Rear, 20 LED Wiring, Partly Painted and Almost Ready for Installation into the Cluster
Step 7 - Rebuilding the Instrument Cluster
Depending on what wires you used for the LEDs you may need to cut some plastic out of the White tachometer housing backing. We ended up not needing to cut anything. The black instrument cover will however need to be cut so the wires can get through. We also installed, some reflective foil, using very thin double sided tape, to make perfectly sure that we did not obscure the backlighting.
|
|
|
|
|
Tachometer Housing Assembly, Showing Wire Routing Access & Reflective Foil for Integrated Boost Gauge
|
|
|
Stock Tachometer Showing Back Lighting and Dark LEDS, and then as Installed in the Cluster Housing Assembly
Bora Tachometer Showing Back Lighting and Dark LEDS, and then as Installed in the Cluster Housing Assembly
This is what we did:

Cluster Fasia Assembly, Showing Examplea of Cuts for Wire Routing for Integrated Boost Gauge
Here is a nice photo of the finished tachometer mounted in the cluster ready to go. If you click on the photo you will see it in action.
Tachometer Installed in the Stock & Borla Clusters, Powered up, Click on photo for In-Action Video
Step 8 - Testing & Wiring Up The Boost Gauge Control Board
This part is pretty straight forward, if you are electrically inclined that is. The LEDs were wired to the Printed Circuit Boards (PCBs) using the wires that we wired in Step 6. It is best to keep the wires as SHORT as possible to reduce any interference or noise, although we never experienced any problems and the circuit is compensated for longer LED leads. 12" should do the trick. This ends up being 5" outside the cluster, this is more than enough so the control box can be tucked away below and to the left of the cluster once installed in the car. It is a good idea to check each LED before you finally solder them to the PCB. If you use a 3k Ohm resistor with a 12v power supply or a 9v battery will also work), you can easily check each wire and establish which LED it represents, then wire it to the appropriate pin on the PCB. Simply connect the +12v lead (or the +9v from the battery) to the common anode wire you marked earlier, then connect the -ve lead to the resistor and touch each LED wire with the other end of the resistor. The appropriate LED will light up dimly in the cluster to let you know all is OK. If you get problems with multiple indicators lighting or an indicator does not light, now is a good time to diagnose and fix it.

Boost Gauge Main Control Unit, Interconnection & Wiring Layout, Not To Scale
It is best to test the whole setup before you put the cluster back in the car just to make sure you have everything all in order. It is far easier to troubleshoot a problem when the cluster is still on the workbench as opposed to being in the vehicle.
Perform the following:
This part is pretty straight forward, if you are electrically inclined that is. The LEDs were wired to the Printed Circuit Boards (PCBs) using the 28 swg cables that we wired in Step 6. It is best to keep the wires as SHORT as possible to reduce any interference or noise, although we never experienced any problems, and our circuit design is compensated for longer LED leads. 9" should do the trick. This ends up being 5" outside the cluster, this is more than enough so the control box can be tucked away below and to the left of the cluster once installed in the car. Final adjustments can then be made with minimum of contortion on behalf of the owner. We found that the stock pressure sensor varied ever so slightly with temperature, so final adjustment after some driving may be called for. Referring to the layout diagram of the circuit board, make sure you get the correct bank on the correct driver chip. Then the PCB was placed in an enclosure and tucked behind the dash. There are three other wires that need to be connected to the car in order for the Boost Gauge to function correctly. The signal comes into the unit from the MAP sensor, we spliced into it directly on the MSD2313. Remember to DISCONNECT the BATTERY BEFORE beginning any electrical work on the vehicle. We simply tapped into the car's vacuum line at a suitable point. There are many of them, choose one that involves the least amount if vacuum pipe to be run from the external sensor. You can run the pipe through the firewall access hole, it is huge and has plenty of room. It comes out behind the ECU in the rear engine compartment. Switched ignition power can be derived from the ECU main wiring loom. We used Pin 1 or Pin 2, one of the two thick BROWN Wires of the large plug for our ground, (BLACK wire on our control unit) and Pin 3 the thick BLUE/BLACK wire for switched +12v (RED wire on our control unit).
The "Dimmer" wire needs to have +12v when in Dim Mode, and ground or floating when in Daytime or Bright Mode. This can be done in many ways. There is a Fuse in the fuse box that is marked "Headlight", you can tap +12v from here. Or, from under the dash you can take the dimmer wire from the power connector harness and splice it into the GREEN/RED or GREY wire on your headlight switch harness. This is the wire that activates the dimming circuit on the control unit when it receives a +12V signal from the parking or main light circuit.

Eaxamples of Boost Gauge Control Units and Enclosure 3.1" x 1.57" x .7" Wired to the Cluster. (Non Sensor and External Sensor Versions
We mounted our control board in a 3" x 1.5" x .7" black plastic enclosure, and drilled a small hole in it for adjustment purposes. You will also notice we installed a plug and socket so we could easily remove the dash in future.
Step 9 - Setup & Calibration
Calibrating the Control Board
Calibration is really simple. Simple adjustments can be done before you even wire up the LEDs. It is best to check some basic voltages. All voltages are respect to the control board’s ground.
Here is what we did:
· There should be about 1.5v on Pin 5 of the Input/Output (I/O) Bank on pins on the PCB. Assuming the external MAP sensor it is connected to the Boost Control Unit PCB.
· There should be about 1.4v on Pin 4 of IC1. This can be adjusted using the Zero Adjustment P1. Turn P1 Anti-Clockwise to increase the voltage and Clockwise to decrease it.
IMPORTANT NOTE: If the voltage on Pin 4 of IC1 is above 2.0v, very erratic and inaccurate readings will result. It is best to set this first to about 1.4v.
When you first power the unit on with the LEDS connected, some of them may be on. Simply turn the 25 turn adjustment trim pot P1 Ant-Clockwise until the first LED is the only LED that is on. Remember Anti-Clockwise Turns the lights off and Clockwise turns them on. If you are in doubt, simply turn P1 Clockwise for a few turns until the lights come on. Then turn the adjustment trim pot Anti-Clockwise until LED 1 just goes out + about 1/8” of a turn. That’s it, you’re done!
Setting up the Dimmer for Night Time
This adjustment is also really simple. You may need to wait until dark to do this. Simply apply +12v to pin 2 of the I/O bank of pins, or just turn on your lights if you have wired it up to the car’s light switch. When in operation the lamps will be noticeably dimmer. You may want to adjust Zero Calibration (P1), with the ignition on but with the engine off, Clockwise to turn some lights on, (only a few of the lower LEDS will be able to be turned on) so a few indicators are on. You can then adjust the dimmer’s night setting adjustment (P2) Clockwise to set them dimmer or Anti-Clockwise to set them brighter, until you get the desired brightness. Once this is complete you may have to re-do the Zero Calibration of P1 as mentioned earlier.
Step 10 - Admiring the Finished Product
The following photos show various close ups of the dash after re-installation into the car.

Completed 25 PSI Unit, in Bora Cluster

Completed 30 PSI Unit in Stock Cluster
We hope you find this article interesting. If you would like more information, please Email us or go to our Gauges For Sale pages.