Ordering 1986 ECM, no auto or manual??? (Page 1/1)
82-T/A [At Work] APR 06, 09:23 PM
Hey guys, long story short... I'm planning on ordering a 1986 2.4 ECM because they converted to the V5 A/C compressor system (which is controlled by the ECM), in the 1986 model year. So it's a no brainer since I plan to convert to the V5 variable compressor.

Question though... my daughter's 1985 Fiero 2m4 SE has a manual transmission, and I know that with that, comes the "shift light" which I like, and I don't want her to lose that.

When I look either on Rock Auto or on eBay, there are tons of them available... but not a single one says it's for an automatic or a manual transmission.


I know specifically the manual transmission one supports the shift light, while the automatic one supports the torque converter. What am I missing here... does it not matter? Should there not be different programming for both? Or... what?
Patrick APR 06, 09:59 PM

I believe it's the PROM, not the ECM itself that's different for a manual vs an automatic transmission.
82-T/A [At Work] APR 06, 10:18 PM

quote
Originally posted by Patrick:

I believe it's the PROM, not the ECM itself that's different for a manual vs an automatic transmission.




Yeah, some of them (on Rock Auto), say that they need to use your old PROM, but others say "no programming needed, ready to go..." so that's where I'm confused. My guess is that they're putting on an automatic PROM, and therefore they cover both bases... but then I'll likely lose the shift light. Not something I'd want to eliminate, because that's super cool... haha...
jdv APR 07, 05:48 PM
Todd you will need to check the wiring and verify that it is correct. You might have to repin or add some wires to the proper terminal on the ecm.
82-T/A [At Work] APR 07, 06:22 PM

quote
Originally posted by jdv:

Todd you will need to check the wiring and verify that it is correct. You might have to repin or add some wires to the proper terminal on the ecm.




Yeah, I was definitely planning on that. I'm going to completely unwind the main harness and will also repair / replace any of the connector ends and inspect all the wiring... re-wrap it, etc. I'm planning on re-routing some of it. I really don't like the wires going down the front of the motor for things like the A/C compressor and such. There's so many better paths that I can go, such as right off the firewall and to the A/C compressor directly.

Thanks!
Stingray92 APR 07, 08:15 PM
Not sure what if any wire you'll need to repair/replace/modify. There are differences for automotive wire, heat, oil, vibration, emi. If you need something specific I like Del-City.
theogre APR 07, 10:33 PM

quote
Originally posted by 82-T/A [At Work]:
Hey guys, long story short... I'm planning on ordering a 1986 2.4 ECM because they converted to the V5 A/C compressor system (which is controlled by the ECM), in the 1986 model year. So it's a no brainer since I plan to convert to the V5 variable compressor.

Question though... my daughter's 1985 Fiero 2m4 SE has a manual transmission, and I know that with that, comes the "shift light" which I like, and I don't want her to lose that.

When I look either on Rock Auto or on eBay, there are tons of them available... but not a single one says it's for an automatic or a manual transmission.


I know specifically the manual transmission one supports the shift light, while the automatic one supports the torque converter. What am I missing here... does it not matter? Should there not be different programming for both? Or... what?

Wrong.
All ECM Does Not Care about what AC System(s) are used. They Only have "Final say" that the AC Clutch Turn On & Off & adjust engine timing etc as needed when On. Example: When you Floor the Gas, ECM Shuts Off the AC during the event.

Just Use Same ECM because in your case is already same ECM # anyway.


You will Bypass the Clutch Cycle Switch required by DA6 & HR6 compressor on the ACC/Drier can in front of car.
Also need to Change the Control Valve In the V5 for using R134.

ECM doesn't about wiring etc because the PROM has right "flags" & code for whatever engine & transmission.
In Stick cars not only changes 1 output pin rules for On/Off but also uses different engine setting overall & have different "Anti Stall" setting too.
AT cars use Same ECM Pin to run TCC locking.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 04-07-2024).]

82-T/A [At Work] APR 08, 11:08 AM

quote
Originally posted by theogre:
Wrong.
All ECM Does Not Care about what AC System(s) are used. They Only have "Final say" that the AC Clutch Turn On & Off & adjust engine timing etc as needed when On. Example: When you Floor the Gas, ECM Shuts Off the AC during the event.

Just Use Same ECM because in your case is already same ECM # anyway.


You will Bypass the Clutch Cycle Switch required by DA6 & HR6 compressor on the ACC/Drier can in front of car.
Also need to Change the Control Valve In the V5 for using R134.

ECM doesn't about wiring etc because the PROM has right "flags" & code for whatever engine & transmission.
In Stick cars not only changes 1 output pin rules for On/Off but also uses different engine setting overall & have different "Anti Stall" setting too.
AT cars use Same ECM Pin to run TCC locking.


Thanks Ogre, this is really good information. MAYBE it's different in the V6, and that's where I was confused. I wasn't sure... but I bought a 1986 Service Manual just in case.

If there doesn't appear to be any difference then (as you say, the ECM doesn't care what kind of compressor), then I don't even need to go to a 1986 PROM anyway.

I'll dig into the manual when I get it, and then share what I find.


Thanks!

[This message has been edited by 82-T/A [At Work] (edited 04-08-2024).]