 
     |
| Manual Swap (Page 1/2) |
|
LS4FieroGuy
|
MAR 02, 01:38 AM
|
|
Hey all. I'm about to do a manual swap on my 88. It's got a 2.5 Duke and an auto trans currently. I'm putting in the Isuzu 5 speed in place of the 3 speed auto. My main question is will I need a different ECM for the swap? It's staying a 2.5.
------------------
Joshua Seeger
|
|
|
|
cartercarbaficionado
|
MAR 02, 03:56 AM
|
|
| quote | Originally posted by LS4FieroGuy:
Hey all. I'm about to do a manual swap on my 88. It's got a 2.5 Duke and an auto trans currently. I'm putting in the Isuzu 5 speed in place of the 3 speed auto. My main question is will I need a different ECM for the swap? It's staying a 2.5.
|
|
yes. different chip or whole ecm and you gotta swap the harness to a manual one.
you can convert the harness but its a real pain in the butt
|
|
|
|
Vintage-Nut
|
MAR 02, 07:54 AM
|
|
It is not 'easy' and pretty involved....
Automatic to Manual 5spd Transmission Swap 88 GT by AustinH
https://www.fiero.nl/forum/Forum2/HTML/000342.html
A Lot of Other Automatic to Manual Threads Too:
https://www.fierosearch.com...nual&Action=DoSearch
One member thinks *this* is easier
| quote | Dennis LaGrua:
What I would do is to replace the automatic with the 4T60 a 4 speed automatic w a shift kit. Thats a much easier almost bolt in conversion. |
|
------------------
Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles
|
|
|
|
olejoedad
|
MAR 02, 08:03 AM
|
|
Actually, all that needs to be done with the wiring is to eliminate the Neutral Safety Switch on the automatic transmission. It's a very simple procedure.
Cut and join the heavy gage yellow and purple wires.
Cut the blue and green wire for the backup lights and wire a plug for the backup light switch for the Isuzu.
Cut and insulated the orange/black and black/white wire ends.
WARNING - The modification eliminates the Clutch Safety Switch feature on the OEM wiring, so the car will be able to be started without depressing the clutch pedal. The car will be able to be started IN GEAR, you need to be aware of that.
Change the ECU or the EPROM.
|
|
|
|
IMSA GT
|
MAR 02, 10:05 PM
|
|
| quote | Originally posted by olejoedad:
Actually, all that needs to be done with the wiring is to eliminate the Neutral Safety Switch on the automatic transmission. It's a very simple procedure.
Cut and join the heavy gage yellow and purple wires.
Cut the blue and green wire for the backup lights and wire a plug for the backup light switch for the Isuzu.
Cut and insulated the orange/black and black/white wire ends.
WARNING - The modification eliminates the Clutch Safety Switch feature on the OEM wiring, so the car will be able to be started without depressing the clutch pedal. The car will be able to be started IN GEAR, you need to be aware of that.
Change the ECU or the EPROM. |
|
I have a question about this. Could the existing neutral safety switch from the automatic be wired to the clutch pedal safety during the swap and act like the factory safety switch on the 5 speed cars?
|
|
|
|
82-T/A [At Work]
|
MAR 03, 08:36 AM
|
|
Going from an automatic to a manual, as others have said, it should work just fine. You actually don't even need to swap out the ECM... you just have to deal with the Neutral Safety Switch.
A couple of things (some are already addressed):
- You will not have a clutch safety switch (meaning you can start the car in gear)
- You will not have use of the shift light, since this is ECM programming
|
|
|
|
olejoedad
|
MAR 03, 08:59 AM
|
|
| quote | Originally posted by 82-T/A [At Work]:
Going from an automatic to a manual, as others have said, it should work just fine. You actually don't even need to swap out the ECM... you just have to deal with the Neutral Safety Switch.
A couple of things (some are already addressed):
- You will not have a clutch safety switch (meaning you can start the car in gear)
- You will not have use of the shift light, since this is ECM programming |
|
I'm not sure if the automatic EPROM needs to see the 12v signal from the automatic NSS that is carried on the orange/black and black/white wires.
|
|
|
|
olejoedad
|
MAR 03, 09:02 AM
|
|
| quote | Originally posted by IMSA GT:
I have a question about this. Could the existing neutral safety switch from the automatic be wired to the clutch pedal safety during the swap and act like the factory safety switch on the 5 speed cars? |
|
No.
The clutch safety carries the solenoid signal to the C500, then to the starter.
The NSS sees the signal from the C500 and closes to allow signal to solenoid.
|
|
|
|
LS4FieroGuy
|
MAR 03, 08:53 PM
|
|
So I saw a few ECMs on Rockauto and I'm wondering if one of those would work.
|
|
|
|
82-T/A [At Work]
|
MAR 04, 07:39 AM
|
|
| quote | Originally posted by LS4FieroGuy:
So I saw a few ECMs on Rockauto and I'm wondering if one of those would work. |
|
I have a diagram somewhere, but the ECMs are the same across the board for certain years... it's the EPROM / PROM that's different, and the wiring harness.
Let me see if I can find it:
EDIT: Yeah... so the ECMs are the same for all years except 1985. The 1985 ECM is actually a bit nicer (I'm told) than the other years, and has provisions for a knock sensor to be installed... just lacks the leads on the wiring harness, and a bit to be flipped in the PROM. But what you'll want to do is get a new PROM.[This message has been edited by 82-T/A [At Work] (edited 03-04-2025).]
|
|
|
