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View Full Version : 99 2.8 Avant automatic Trans Swap, Car wont start...HELP



shantiwitt
02-22-2016, 12:21 PM
Hi,

I have a 1999.5 A4 Avant with the 2.8 V6 and the 5 speed triptronic transmission. I bought the car with 211k miles and a bad trans for $325. I recently swapped the trans with one out of a '98 1.8t.
The car started up everytime prior to the trans swap. Everything went well until we tried to start the car when we were done with the swap. We turned the key and nothing happened.
First thing we checked was to see if the started was getting power, which it isnt. We know the battery is charged and can hear a relay clicking when we turn the key. We noticed that the dash said "engage clutch to start the car" and thought it was odd (it had done this before we pulled the trans but didn't think much of it). We thought the TCM might be bad so we pulled up the carpet on the pass side of the car and sure enough the TCM was completely submerged in standing water (apparently this is a problem with b5s). We swapped TCMs with the one from the '98 and then the dash started to say, "shift to park and apply brake to star." Much better than apply clutch. But still the car won't start. The dash dsiplays the gears correctly.
We were recieving 2 codes, p1626 and p1545. We were able to clear p1545 but not p1626.
Things we think might be wrong, The new TCM might not work with the V6, the multifunction switch might be bad (but the dash displays the correct gear).
Please provide any feed back possible, this has been a nightmare for over a month!

Thanks in advance!

Rodgman15
02-22-2016, 12:55 PM
Pretty sure you need to recode the ECU to a manual trans. I could be wrong though. Hook it up to vag-com and give it a crack.

Nollywood
02-22-2016, 01:18 PM
I would check the earth strap on the block to frame (starter motor side).

Oops. I've just re-read your post, you say the starter motor isn't being energised. So there is a break between your ignition switch (term. 50) and the starter motor.

Check ignition switch:

Is getting 12V+ (term. 30).
If the above checks out, make sure term. 50 is outputting 12V+ when ignition is in start. If not, contacts are burnt.
Check the slot in the plastic cam that accept the steel peg is not split, or broken.

Have you tried starting the engine from the starter motor itself, by bridging the 2 large terminals with a flat screwdriver (ignition switch on)?

shantiwitt
02-23-2016, 01:47 PM
Pretty sure you need to recode the ECU to a manual trans. I could be wrong though. Hook it up to vag-com and give it a crack.

It is still an autotrans

Rodgman15
02-23-2016, 01:48 PM
I obviously missed that, sorry. Good luck to ya!

walky_talky20
02-23-2016, 01:56 PM
TCU should have nothing to do with starter solenoid activity. (Although a wet TCU may have caused all of the original trans issues!) The circuit goes:

Battery > Ignition Switch > Starter Relay > Starter Solenoid <<**I kid you not: there isn't even a fuse in the circuit.

The starter relay does have a second input (a ground for the coil) which goes:

Ground > MultiFunction Switch > Central Lock Module > Starter Relay

If your Starter Relay is clicking, then you are most likely getting good 12v+ from the ignition switch and good Ground from the MultiFunction switch. HOWEVER, check carefully - the "click" from the 75X Load Reduction Relay (which clicks OFF when the key hits the Start position) can fool you. Best to pull the relay and see what you are actually getting at the terminals. Better yet, bypass the entire starter relay and see what happens. Rules out a bunch of crap at one time.

shantiwitt
02-25-2016, 06:06 PM
TCU should have nothing to do with starter solenoid activity. (Although a wet TCU may have caused all of the original trans issues!) The circuit goes:

Battery > Ignition Switch > Starter Relay > Starter Solenoid <<**I kid you not: there isn't even a fuse in the circuit.

The starter relay does have a second input (a ground for the coil) which goes:

Ground > MultiFunction Switch > Central Lock Module > Starter Relay

If your Starter Relay is clicking, then you are most likely getting good 12v+ from the ignition switch and good Ground from the MultiFunction switch. HOWEVER, check carefully - the "click" from the 75X Load Reduction Relay (which clicks OFF when the key hits the Start position) can fool you. Best to pull the relay and see what you are actually getting at the terminals. Better yet, bypass the entire starter relay and see what happens. Rules out a bunch of crap at one time.

Update: Spent the afternoon today to resolve this. Started by swapping Multifunction switches from the old trans that we knew worked. Then we checked everything way to the starter relay and everything seemed to be in order. Relay had 12V and still wouldn't start. Then we went to the starter and there was nothing. Eventually we found a plug on the firewall that was not seated properly and wasn't making full contact. Turned out it was a wire that went to the starter solenoid. Once that was in order we cleaned the connector on the original Multifunction switch and then everything worked fine. Fires every time now. Thanks for the help