Gas pedal won't press, car won't start
 

I apologize if this is an issue that has been discussed in another post, I have searched and just couldn't find something that closely resembled this.

A family member, who has driven my car many times before and does so when I'm away from home for more than a few weeks, was driving my car last night when without warning or error code the gas pedal became stiff - very difficult or impossible to press down. She was able to pull the car over to the side and when trying to restart the ignition, the car would not start. Thinking it may be the battery, a friend came over with jumper cables but this did not start the car. We had to have the car towed.

I'm going to get the car checked out but before that, does anyone have an idea of what could be going on - gas pedal won't press, engine won't start?

This is an early 2005 Audi A4 (b6), 1.8t, manual

I would have the codes read on it. I'm thinking its related to the throttle body. I believe there is a sensor on your gas pedal....Accelerator Pedal Position Sensor...

it also could be the sensor 'locking' the pedal because something else is telling it to.....since it won't start. A stuck throttle cable would let you start it at least.......

Have the codes read, and that should give you a starting point....

Bad fuel pump?
 

Ok, so I got some more details. Unfortunately I'm not there, wasn't present when the problem occurred, and won't be there for another few months. I don't want to let my car sit like this for a few months so a friend of mine is gonna try to take this car to the shop.

Apparently when the car died, there was the battery symbol flashed on the console, the steering wheel became really hard to turn, and the gas pedal wouldn't press down. However after trying 30 min later, we were able to press the gas pedal down proving that it's not locked.

We don't think it's the battery since the dash lights are still turning on and we're able to crank the engine, so I'm guessing it's a bad fuel pump. But if it was the fuel pump, would we have gotten a different symbol flashed on the console or an error code on the console? Do these symptoms indicate a bad fuel pump?

Also, something to note...as far as I know, B6's don't have throttle cables. I believe they are all throttle by wire...i.e computer controlled.

scanner
 

Will have to tow this vehicle to get it checked out since it won't start. I really need to scan it as you've mentioned to get some info about what is really wrong before I pay for the costly tow.

Can you recommend a decent scanner that's not too pricey? I read that some scanners are not compliant for some models? And will not read the codes of 2005+ models?

Thanks for all of you help guys. I have new information. A scanner was used, but no codes could be gotten evenen though the scanner (Innova 3040) is suppose to work on Audis. Also the ignition switch activates the fuel pump relay switch, but no current flows through the fuel pump circuit. Another post on this forum showed that this can be caused by a bad ignition switch. So how do you remove the ignition switch?

Here you go. Takes little to no time. Make sure you have the correct new switch...they're under $20 if I remember correctly.

AudiWorld Tech Articles

Thanks. I need to test the switch to see if it is indeed the problem and if so I'll try to switch it out. Will keep you updated.

Ignition switch not the problem
 

Well it looks like the ignition switch is not the problem as that tested fine.

A friend of mine back home did some testing with the connections and found that there must be a short somewhere that is preventing the fuel pump from running. I'm hoping the solution can come about by replacing wires or connections and not the entire fuel pump. Here are our findings, can you let me know what you think:

1) I tested both the new fuel pump relay switch and the old one and they both tested fine outside the car. I tested the two power circuit terminals on each relay and they had a huge resistance. I applied 6 V across the two control circuit terminals, and the resistance across the two power terminals dropped to 0. Also, whenever I applied 6 V across the control circuit terminals, the relay emanated a clicking sound.

2) I used my tester (light) to check all of the wires going into the ignition switch, and they tested out OK. That is the appropriate wires had a voltage in the OFF, ON and START positions. I measured the voltage in the case of the wires that went on in the ON position and they all had 12 V.

3) All of the fuses in the fuse panel are OK.

4) The last time I tested the fuel pump relay terminals with a voltmeter, they tested fine. That is, with the relay unplugged, the positive power circuit terminal has 12.5 V all the time, the ground for the power terminal is 0 V. The positive terminal for the control circuit is 0 V when the key is turned OFF, but jumps to 12.5 volts when the key is turned ON and stays there in the START position. The voltage on the ground of the control circuit is 0 volts when the key is in the OFF position. All of the times I tested the fuel pump relay, the upstream power terminal was always 12 V (ignition switch ON or OFF) and the upstream control circuit terminal always tested 12 V when the Key was turned ON. It was 0 V when the key was turned OFF (But see below for variation in the downstream power terminal).

5) At the fuse panel with the fuel pump relay plugged in, the upstream terminal for the fuel pump relay fuse (#28) measured 0 V the last time I measured it when the key is turned OFF and also when it is turned ON. There is no resistance between the downstream power terminal of the fuel pump relay (fuel pump relay unplugged) and the upstream terminal of fuse 28.

6) I put 12.5 V from the battery on the downstream terminal of fuse 28, but the fuel pump did not go on. The fuel pump has four terminals, two very large and two small. I put 12.5 from the battery across the two large terminal making sure the polarity was correct, but the fuel pump did not turn on (fuel pump still in car). I am guessing that it might also have a control relay on it that needs to be activated (two smaller terminals), but I was afraid to apply any voltage across them because I was unsure what they are for.

It seems that there might be a short between the power circuit of the fuel pump relay and the fuse board.

I tested the fuel pump relay and fuse board several times, and I noted some unusual behavior. What I described above is true for the last time I checked it. Most of the time when I connected my tester (light) to the upstream side of fuse 28 (fuel pump relay plugged in), it was off when the ignition was both OFF and in the ON position. However, two times today, the light on my tester switched on for about a second or two when I turned the key on but then the light went out even though the ignition key was in the ON position. I turned on the ignition key again several times immediately after, but the light would not go on, not even for a second. I did this again 10 min later, however, and I could replicate these findings. That is, my tester light went on for a second or two when the ignition was turned ON but the tester light went out while the key remained on, and I could not repeat this phenomenon.

I then put a voltmeter on the upstream terminal for fuse 28 and I noticed that it registered 2 V when the key was turned OFF. When I turned the key ON it still registered two volts. I then pulled out the fuel pump relay and measured the voltage on the downstream power terminal and it measured 2 V. The upstream terminal measured 12 V as usual.

Since the power circuit from the fuel pump relay goes to fuses 28, 32 and 34, I pulled out fuses 32 and 34 and measured the voltage at the upstream side of fuse 28 with the fuel pump relay in and the ignition turned ON, but it registered 0 V. For this last test, however, the voltage at the upstream terminal of fuse 28 was reading 0 when the ignition was ON or OFF.

I am guessing that there might be a short (see above) or else there is some problem with the computer or sensors.

Resolved
 

Well, just wanted to update and close off with the resolution. Turns out it was a bad fuel pump. We tested all components and everything was getting the right amount of power and since the fuel pump still wouldn't run we figured it had to be the culprit. We got a new fuel pump and replaced it with the help of some great write-ups and videos. My take-away from that process is if you are quite meticulous and methodical, you should be able to replace the fuel pump yourself without too much fuss and save a chunk of change in labor. Thanks to all who read and gave me their advice.