Code Free

My friend (and TDI Mechanical Guru) Justin visited last night, and we made some progress on the VAG-COM codes. We had a minor discovery with the accelerator pedal controller as well, but overall, it was a very positive few hours. That "red ball" project has moved on, and work has settled a bit. We'll see how long that lasts....

Code Free
Justin arrived before I got home from work, ready to get the bus running. He confirmed that seeing the mileage on the dashpod was a significant step, and was able to get his VAG-COM reading application on his laptop to communicate with the engine computer. He brought a 99.5 Jetta harness with him - the complete harness for the entire car. We picked through the harness and noted a single 2-plug connector that hooked the smaller engine harness with the other engine-ish harness. Connecting this did not relieve any codes, but it reminded us of the research I mentioned in the last post about all of the codes appearing on elements contained within that same harness. We took his 99.5 harness and hooked it into my engine, leaving the glow-plugs disconnected, to test this theory. VAG-COM was unable to find any error codes / faults. For the time being, I'll be leaving the 99.5 harness in-place and removing my 98 harness. I'll find the bad connectivity wire and fix it off-line. Meanwhile, this resolution brought us to the edge of being able to start the engine.

Clutch Pedal switch
For some reason that I really don't understand, VW included a switch on the clutch pedal to prevent anyone from being able to start their car with the clutch out. I suppose there were complaints about this, or maybe this is one of those Ralph Nader safety things, but I think its pretty stupid. Accidentally trying to start it in gear has its own notification system: that uncomfortable lurch followed by not starting. Anyway, this switch needs to be depressed to allow the starter to get the signal to start. In the early TDI (ALH model), the switch runs through the comfort system, which I tore out. The only signal that matters, though, is a single signal from that system to the #3 relay (number 185 printed on the top) which is the starter lockout relay. That relay takes start-switched power (50b) and routes it to the starter solenoid when 12V are applied to the relay switch from the comfort system wire. Since the send-side of the relay only has 12V when the ignition is turned to "start", the relay, the comfort system, and the clutch pedal switch are not needed... in my application. We jumpered across the relay, and got around the clutch switch problem.

Still NOT Starter-ing
After we got around the clutch pedal switch, the starter still wouldn't turn. To rule out a bad starter, we sent a test wire directly from the solenoid to the battery and proved that the motor turned. Unfortunately, we discovered that the spacer that I introduced between the adapter and the starter caused the teeth on the starter to fail to reach the flywheel. I will be removing the starter, removing the spacer and re-installing the starter. Figure 30 minutes, but unfortunate that it stood in the way. Also, this indicated that the wire running from the relay to the starter solenoid had a break in it. I will need to cut up the wiring zip-ties and find the continuity break. Since there are 2 splices, it shouldn't take long to find which splice failed.

Throttled
Our last discovery was that the direct connection of the bus accelerator pedal to the throttle switch was pre-loading the throttle signal. This means that even without a foot on the pedal, the computer thought we were trying to be at about 35% (not 0%). This is because the old pedal needs some kind of pull from the old carburetor to keep the pedal upright. I will add some space between the throttle switch and the pedal and add a return spring to provide that pressure. That shouldn't take me very long, once I find a return spring.

That's it for today. There was a lot of progress, and the outlook is very bright. I won't be able to put much time in over the next few weeks for travel reasons, but I know what I have in front of me. First, fix the starter signal, R&R the starter and prove the starter can turn the motor. Then, fix the accelerator pedal bit. Once I have that, I'll re-focus on the air cleaner (AMSOIL) and air-source for the vacuum and then look for the break in the engine harness so I can give Justin's back to him. As always, thanks for following along and enjoy the rest of your summer-

TDI-FEST: Portland, OR Labor Day Weekend