OK - so i found this diagram of the ECM connectors in the 1987 Assembly Manual. How do i tell what the wires go to (e., g., what wire connects to A1) (!?) Can someone post the key/legend or tell me where it is ?

[This message has been edited by PaulJK (edited 11-27-2009).]

4 or 6. Do you have a copy of the 86 service manual downloaded. It will tell you what you need to know.

are those ALL the ECM connections or are there more on other pages ? For some reason, I have all the cruise control wires going into the ECM - looks like they might be going IN one connector and back OUT the other (then going into the engine compartment to the cruise control).

can you tell me what page or section that's in ?

[This message has been edited by PaulJK (edited 11-27-2009).]

The cruise wires go to the cruise module stuffed under the driver's side carpet against the tunnel unless someone changed to a later PCM that had the cruise functions built in. Other than the VSS signal for speed, there is nothing common between the ECM and cruise.

In Fiero... Only 87-88 L4 ECM has cruse control build in. All other use separate Cruse module.

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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 (It's also at the top of every forum page...)

quote Originally posted by theogre: In Fiero... Only 87-88 L4 ECM has cruse control build in. All other use separate Cruse module.

If you dis-connect the cruise control wires from this ECM, will it ONLY dis-able the cruise control (?) or do the cruise control wires provide other info that the ECM uses?

Do you happen to know where the legend is for the diagrams in the manual (as above) ?

THANKS everybody.

[This message has been edited by PaulJK (edited 11-27-2009).]

So I take it you have an 87 or 88 L4? Would be helpfull of you posted that information from the start.

Someone that has a manual for those years would have to post that information.

Your posts indicate you have access to a service manual. You posted a diagram for the 2.8. But if your stalk cruise control wires run to the ECM, that's indicative of the 87 2.5 (as per Ogre's statement). If you have a 2.8 with the stalk's cruise control wires running to the ECM, that's odd. If you have access to the service manual, the information you need is on page 6e2-a-6 for the 2.5. this is the pin out for the c1 and c2 connectors. Use this in conjunction with the schematics on 8a-34-2. As TK indicated only the speed sensor signal (comes off the instrument panel) into the ECM is common for the Cruise control and other functions. Don't disconnect that from the ECM. And as the schematics indicate, the cruise control part of the 2.5's ECM is reading brake switch, clutch (for manuals), cruise stalk settings, transmission switch (for automatics), speed. FYI, the cruise control stalk connections for the 87 2.5 connect to the C1 connector at 4,20,21.

What are you going to do with it? Fix it? Take it out? It matters.
What year, engine, and tranny?

------------------
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 (It's also at the top of every forum page...)

quote Originally posted by theogre: In Fiero... Only 87-88 L4 ECM has cruse control build in. All other use separate Cruse module.

Dang it, I forgot. I really need to actually look at an L4 sometime!

quote Originally posted by Dodgerunner: So I take it you have an 87 or 88 L4?

Nope, that's why i'm puzzled. The part number on the ECM is # 1227748 - does this tell whether it is L4 or V6 ECM ?

quote Originally posted by goldiron: If you have a 2.8 with the stalk's cruise control wires running to the ECM, that's odd.

Yep. I have the Assy Manual and the MultiMeter trying to sort things out . Thanks VERY Much - i found the stuff you mentioned and the corresponding info for the V6 .

quote Originally posted by theogre: What are you going to do with it? Fix it? Take it out? It matters.

I took out the vacuum cruise control and i'm (1) putting in the electronic cruise control (per threads by Fino and Darth) and cleaning up some wiring issues.

[This message has been edited by PaulJK (edited 11-27-2009).]

well the 748 ecm is for an 87-88 L4 engine...
If you hvae a V6 then the engine must have been changed or something...

Thanks very much for helping me sort this out . If i cut the cc. wires fgoing into the ECM, do you know if it will hurt anything other than disabling the ECM cc functions (?)

[This message has been edited by PaulJK (edited 11-27-2009).]

My guess and it's only a guess, I doubt it would hurt anything.

i examined the assy. manual diagrams for the L4 ECM (driveability, etc.) and cruise control. There aren't any cross-connections (that i could see) in the cruise control. This seems to make sense - the cc option would need to be "stand-alone" for cars to be offerred witthout the option. If not, cars without cc. would need a different ECM (?)

I'm starting to get brave about dis-connecting the cc STALK wires ( I'll leave the power and VSS ) from the ECM and running them directly to the electronic cruise control mudulein the engine compartment. It most likely wouldn't hurt anything and I could always re-connect them later if needed. Does this make sense (?)

[This message has been edited by PaulJK (edited 11-27-2009).]

sounds like a plan.

You pull cruse in 87-88 L4? You should have fix it... Cruses is build into ECM. ECM can stream cruse option in data. Data stream can help you if switch is bad, etc.

You think you are doing a upgrade but 87-88 L4 is better left alone.

Anyway... If you are sure...

You and Dodgerunner is wrong picture. You not needed the ECM...

See small harness connection near ECM? 8 pins and 6 wires use, 1x1.25x1.5, is name C255.

Disconnect or Cut from ECM. That's it. ECM will not care. If you cut, make sure it can't short.

C255 pin out: (Check on 87. 88 maybe different.)
Pin Function
A Set/Coast
B Brake
C Resume/Accelerate
D Cruise On
E Not Use
F Not Use
G Servo Vacuum
H Servo Vent
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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 (It's also at the top of every forum page...)

[This message has been edited by theogre (edited 11-28-2009).]

thanks much ogre - last night i removed the C245 (?) and re-pinned the wires into the C255 (?). A lot of work, but it's Very clean

[This message has been edited by PaulJK (edited 11-29-2009).]