_Bigwormfab

Hey all, first time poster long time reader. So I just finished my s5 t2 swap into na s4 convertible. Everything went swimmingly until I went for the first start after the swap. I have power to everything (radio, dash, gauges, headlights, convertible top, etc.) but when i turn the key everything goes dead until I turn it back to accessory. I tested the starter and I have 12v when the key is initially turned and then drops to 3v and then to 0. The starter is brand new. Does this indicate a short? My battery wires also get warm after a few turns of the key. Im not familiar with automotive wiring so I don't even know where to begin.

Btw as I mentioned its s5 t2 swap into s4 na convertible. Emissions delete, omp delete, using all s4 t2 electronics: tps, pressure sensor, afm with the na harness and convertible ecu (heard it works with the t2, info on that would be great also!)

Thanks!

satch

iTrader: (1)

The starter is activated by the spade wire connected to it and not the thicker wire coming from the battery. Which wire are you checking. The heat you are seeing is from resistance in the wire(s) thus something is obviously wrong such as poor connections at the battery terminals or also at the starter. The ground wire from the battery runs to the strut tower first before running to the starter's mounting bolt. The positive battery terminal runs straight to the starter. you need to recheck these. Most of the items such as accessories are not used for starting the car thus they briefly go dead w/key to start such as lights, radio etc.

OG BBF

As above.
Hot wires can indicate bad ground connections or insufficient gauge wire being used. Also as mentioned the smaller gauge wire with spade connector is what activates the starter motor solenoid. Once the starter receives voltage from this wire the solenoid is activated which allows the 12v in from the fat battery cable to crank the starter/engine.

-verify your grounds are clean and secure(make sure you have an engine 2 chassis ground)
- verify secure battery cable both ends
- check the smaller starter motor solenoid wire has voltage when key is on ign position.

misterstyx69

iTrader: (142)

Will the engine spin freely if you move it by hand?
If so then you can rule out the engine stopping the starter from turning.
Next is to take 12 volts and apply it to the starter itself..Direct..not thorough the Wiring..
IF that works then your wiring is suspected.(BE CAREFUL..not smart to do while the car is on the ground!..and you are under it!)
You should go through the wiring and clean the connections up to the starter and engine,battery,chassis if so.

_Bigwormfab

I have jumpered the starter, assuming that's what you mean by testing the starter directly. I can feel the starter move initially once the key is turned but immediately stops after 12v drops. Gonna start with cleaning connections as you mentioned above. Btw engine does in fact spin nicely by hand

OG BBF

As in give the starter a direct live feed. You say it cranks when key is turned but voltage drops and it stops. You need to also verify the starter is not faulty, solenoid might be faulty. You don't need to remove the starter but best way to check is to take it out.....get some wire and attach it to where the positive fat wire goes and where the smaller solenoid poster wire goes, then attach to + terminal on battery then take another wire, hook it up where the ground goes on the starter. Then when you touch this wire to the - terminal on the battery the starter gea should extend out ans start spinning. It will spin for as long as you keep the wires connected. If this doesn't happen your starter is the issue.

_Bigwormfab

Dang! I wish I knew how to do this sooner! I had a used t2 starter and ended up buying a brand new one because I thought it was toast. Just tested both and they're both working properly.. Guess it doesn't hurt to have a backup so now that I know my starter isn't faulty, do I begin with checking the solenoid wire?

OG BBF

Hehe we live and learn remember a car runs on a 12v electrical system so pretty much anything can be tested off the car with this method unless it's part of a more complex circuit.

Well that's great! At least we know the starter is fine, so we can tick this off the list.

Key thing to focus on now it's the connections. The hot positive wire is of concern, and could be the reason your having issues due to high resistance. As stated before check earth connections are clean and make sure the battery positive wire is in good condition, and that it's properly secured to the terminal, ensure there's no corrosion (if it's the factory cable it's old so may internally be corroded causing the resistance. Also do a voltage drop test to see if your starter is getting a full 12v from battery or is it losing power. Here's a great link on how to perform a voltage drop test. Try all that and let us know how you get on

http://www.aa1car.com/library/voltage_drop_testing.htm