S4 to s5 alternator wiring issues
04-24-20, 02:49 PM
#1
Full Member
Thread Starter
Join Date: Feb 2017
Location: Comox valley, british columbia
Posts: 81
Likes: 0
Received 0 Likes
on
0 Posts
S4 to s5 alternator wiring issues
I have a 1989 s4 gxl with a s5 t2 swap, it got the engine rebuilt and hasn't fully been broken in yet other than idling. It has a lot of shotty wires ive been cleaning up.
before cleaning up said wires it had been idling very smooth and starting easily every time, however once it got up to temperature the idle would drop from 1000 and jump to 2500rpm repeatedly, i havent had the chance to figure out the cause of that yet, i was thinking tps or something.
I rewired crappy connections behind the left strut tower, i did each connection one at a time as to not mix the wires up. Using good crimpers and good heat shrink butt connectors and doing the tug test.
It has a brand new negative ground cable going to the strut tower then to the starter.
the positive cable could use replacing so im definitely going to do that once i figure out the alternator wiring.
When i put it back together it was hard to start and when it does start it shakes a lot and idles under 700 rpm almost as if only one rotor is firing, i realised the battery was at just under 12v and higher rpms didnt change that. So i guess the alternator isnt charging now.
The alternator connector has 2 wires, "S"and "L". As well as the B connector to the alternator stud.
the B connector is connected straight to the battery, and the S pin goes from the battery -> 30a fuse in the fuse box -> alternator and has 12v constant.
the L pin currently has no voltage even when key to on
its my understanding that on an s5 car this "L" wire would go from the alternator through a series of plugs to the check alternator light then to the fuse box or something like that,
Right now the "L"wire is cut and routed across the engine bay into the firewall and into a x-15 plug, and still has no power with key to on at this location.
so my question is, shouldnt this wire be wired to the check alternator light in an s4 car the same as the s5? So it should just go from the alternator to the wire that goes into the dash to the alternator light?
On a side note the alternator has no continuity or resistance between the "L" pin and the alternator body, which the fsm says its supposed to.. so im guessing im needing a new one.. or an upgrade. What alternator upgrades and swaps are people doing in 2020? And would the wiring be similar?
before cleaning up said wires it had been idling very smooth and starting easily every time, however once it got up to temperature the idle would drop from 1000 and jump to 2500rpm repeatedly, i havent had the chance to figure out the cause of that yet, i was thinking tps or something.
I rewired crappy connections behind the left strut tower, i did each connection one at a time as to not mix the wires up. Using good crimpers and good heat shrink butt connectors and doing the tug test.
It has a brand new negative ground cable going to the strut tower then to the starter.
the positive cable could use replacing so im definitely going to do that once i figure out the alternator wiring.
When i put it back together it was hard to start and when it does start it shakes a lot and idles under 700 rpm almost as if only one rotor is firing, i realised the battery was at just under 12v and higher rpms didnt change that. So i guess the alternator isnt charging now.
The alternator connector has 2 wires, "S"and "L". As well as the B connector to the alternator stud.
the B connector is connected straight to the battery, and the S pin goes from the battery -> 30a fuse in the fuse box -> alternator and has 12v constant.
the L pin currently has no voltage even when key to on
its my understanding that on an s5 car this "L" wire would go from the alternator through a series of plugs to the check alternator light then to the fuse box or something like that,
Right now the "L"wire is cut and routed across the engine bay into the firewall and into a x-15 plug, and still has no power with key to on at this location.
so my question is, shouldnt this wire be wired to the check alternator light in an s4 car the same as the s5? So it should just go from the alternator to the wire that goes into the dash to the alternator light?
On a side note the alternator has no continuity or resistance between the "L" pin and the alternator body, which the fsm says its supposed to.. so im guessing im needing a new one.. or an upgrade. What alternator upgrades and swaps are people doing in 2020? And would the wiring be similar?
Thread
Thread Starter
Forum
Replies
Last Post
The Shaolin
2nd Generation Specific (1986-1992)
9
09-14-15 07:50 PM
deftones1868
2nd Generation Specific (1986-1992)
5
09-08-13 10:43 AM
lunardeathgod
2nd Generation Specific (1986-1992)
11
05-20-11 10:40 AM