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17 votes
Accepted

How does the tachometer on my dashboard actually work?

While i'm not sure if there are mechanical tachometers like speedometers electronic tachometers are quite simple. An electronic tachometer works like an old analog volt meter. The speed of the engine ...
  • 15.9k
13 votes
Accepted

What is this thing hanging from a wire from the front headliner at the top of the windshield?

Figured out it (thanks to a shove in the right direction by @mikes): It's the remote engine start accessory's antenna. I didn't think of it when I was asked if I had "add-ons" because it's an ...
  • 501
9 votes

MAP sensor covered with gasoline

When I looked online, here's what I found about the location of the MAP sensor in your car. As always, a picture is worth a thousand words: From looking at other info about that car it's port ...
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8 votes
Accepted

How much distance would 1mm off front brakes translate into?

Here's a rough approach that should work regardless of vehicle You will need to know the current brake pad thickness the thickness of a brand new brake pad how much mileage you've put on the car ...
  • 39k
8 votes

Tricks for disconnecting sensor connectors

Unfortunately there is no "one-size-fits-all" recipe, but here are some general guidelines: Half the battle is in understanding how it disconnects The chances of me damaging a connector due to ...
  • 39k
7 votes

Why don't thermostats have a sensor?

It might seem easy to integrate a sensor that detects the opening/closing of a mechanical thermostat's pintle (LVDT, for example) but here are some challenges which would need to be addressed: Cost ...
  • 39k
7 votes
Accepted

97 Honda Accord won't start after head gasket replacement

You need Spark, Fuel, and Compression for an engine to run. Since this engine was just reassembled, there is a lot to question. Spark - rotor position - beware of caps where the points are not "...
  • 8,413
6 votes

Since when is CAN bus mandatory for new vehicles?

There is a distinction that needs to be made between: OBD: this is an interface, that specifies the physical and electrical parameters required to connect a diagnostic computer and the car's ...
  • 1,282
6 votes

what sensors and formula are used to control VGT/VNT turbos?

Dodge installed VNT Turbochargers on cars in 89 and 90. The most well known of which is the 1989 Shelby CSX-VNT. The vanes were controlled by a dual port vacuum actuator. There was nothing ...
  • 8,413
6 votes
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Replacing a dashboard for another one with more indicators

The basic answer to your question is: Yes To be more specific, I cannot tell you if it will work or not. It appears you already have the specific dash version you want. What you can do is install it ...
5 votes

Malfunctioning Ambient Temperature Gauge - 2004 Subaru Forester

Sounds like the temperature sensor is broken. A new one is $40-$55, and it's a 30 minute job to replace if you've never done it before (it lives behind the grill in front of the radiator). Not ...
  • 8,602
5 votes

Shouldn't my post-cat O2 sensors (lambda probes) be reporting varying numbers?

Here's how to decipher INPA lambdaintegrator Short-term fuel trim. Both banks have a short-term correction of 28%. This should settle down to 0% fairly quickly, so the fact that it stays red ...
  • 39k
5 votes
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What are the safety sensors & cameras on those new windshield packs? (like Volvo city safety)

There are 3 basic aspects; cost, weather and redundancy. Sensors like LIDAR are great at mapping the surrounding world and creating a point cloud. The problem is that high quality LIDARs are very ...
  • 15.9k
5 votes

Jeep Patriot RPM Gauge bounces / not right

I don't know for sure, but would bet the gauge itself is bad. One way you could check this is by putting an OBDII reader onto the port and check live data from the ECU to see if it matches what's ...
4 votes
Accepted

Can I fit parking sensors on the front of my car?

Yes, you can put them in the front bumper. You'll need to drill them in - just like the back bumper. I would recommend having a cut off switch for the front sensors somewhere in the cabin, otherwise ...
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4 votes

Car won't reach operating temperature

The thermostat would have been my first guess too. It doesn't need a sealing ring, the housing will slightly clamp it when you put it back together. It is entirely possible that the temperature ...
  • 1,668
4 votes
Accepted

Are torque sensors used to reduce cam belt failure damage?

Good question. My answer is, probably not. With a caveat; it depends on the speed of the failure. Sometimes bearings will become excessively noisy before they fail. In this scenario the vehicle ...
4 votes
Accepted

Corolla 1999 - My parking brake light randomly turns on and off

As well as being a parking brake warning light, that is also a service brake warning light - i.e. it warns you of problems with the main footbrake. Given what you have described, my first thought ...
  • 28.6k
4 votes
Accepted

Slightly low MPG - need help with my checklist

Sounds high for a car with a 2.0 liter engine. I used to have 1989 Opel Vectra with 2.0 8V SOHC engine, and the consumption was around 8-9L/100km. But then again, if you drive mainly short trips in ...
  • 13.9k
4 votes

Why is it still overheating

There are a few causes of overheating that wouldn't be fixed by your previous repairs. System not pressurising: The radiator cap needs to seal pressure in. If it doesn't, your coolant will boil at a ...
  • 12.1k
4 votes
Accepted

Does the dash temperature sender unit also provide input to the ECU?

For your 626, I'm seeing two different temp sensors listed. I'm seeing this single bladed one: Which shows to be associated with the gauge. I also see this two bladed one: Which I assume is for the ...
3 votes

97 Mazda 323: Where is the IAT sensor?

OK, so it seems like the IAT on this model is integrated with the MAF:
3 votes

Since when is CAN bus mandatory for new vehicles?

The two requirements are separate. OBDII is required in all vehicles since 1996. This is primarily an emissions related regulation to formalize how vehicles would relay emissions failures to the ...
  • 1,587
3 votes

1995 VW golf Mk3. need to know where to find camshaft position (hall) sensor

If your engine is the ABA engine, it's located in the distributor. You have to disassemble the distributor in order to get it out. For the money, they suggest it's a good time to replace the entire ...
3 votes
Accepted

How Much Deviation from Ambient Temp is Normal for IAT sensors?

Most of the time, intake air temperature is not the same as ambient air temperature. This is because the air absorbs heat from the hot engine bay area before the intake air temperature sensor (IATS) ...
  • 39k
3 votes

what sensors and formula are used to control VGT/VNT turbos?

Disclaimer: I've never done this practically. This answer is based on my somewhat limited exposure to turbomachinery theory in automotive applications. It's all about the flow Unlike fixed-geometry ...
  • 39k
3 votes

2002 Yamaha YZF R1- Fault code 15

The fault code is related to your TPS Your TPS is a throttle position sensor. The fault code is not necessarily indicative of a broken wire although it could be. It sounds as though you have ...
  • 32.8k
3 votes

Shouldn't my post-cat O2 sensors (lambda probes) be reporting varying numbers?

It may depend on how you are gathering that data. Perhaps a "Live Data" OBD Parameter ID or "PID"? You may need a more specific scan tool or smarter software. Some (especially higher end) vehicles ...
  • 12.3k
3 votes

How to remove sensor for rear tailgate

I don't know which way the switch would work with it being open or closed to denote the the hatch being closed. What I can tell you is to remove the switch so you have access to the wiring. Cut the ...

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