Having problems with your electronic cruise control install working using my wiring instructions posted here:
http://www.gmtuners.com/files/electcrz.zip ? If so, here are a couple of things to check:
How do you have the cruise module's VSS input wired up? If to a later-than-Fiero ECM, do you have anything else running off of the ECM's VSS 4000 ppm output such as the Fiero's speedometer? If so, make sure this cruise module wired/spliced directly up to the VSS signal output as it comes out of the ECM before that signal goes thru a conditioner/buffer circuit for the Fiero speedo. You could always try disconnecting everything from the ECM VSS output except for the cruise module and see if it works. That might tell you if something else you have hooked up to the VSS circuit is interfering with the cruise unit. If you are trying to use the digital cruise setup in a stock Fiero (using a stock Fiero ECM), you may need to get a speed sensor signal another way -- see this thread for details:
https://www.fiero.nl/forum/Forum2/HTML/090358.htmlIn my wiring instructions there is a relay you are instructed to wire up. The electronic stand-alone cruise control modules need two brake switch inputs in order to work. One input (ppl wire) needs to see 12v + voltage with the ign key on and no brakes applied and needs to see that signal drop to GROUND when brakes are applied; and the other input (wht wire) expects to see the opposite. The relay accomplishes this task using the existing brake signal in the Fiero wiring (for the original Fiero cruise control). The relay wiring method in my instructions was put in there to simplify wiring and avoid certain potential Fiero wiring issues, especially in manual transmission applications. If you do not install and wire up the relay as instructed in my wiring directions, the cruise unit will probably not work at all.
If all the above checks out but your cruise still doesn’t work, you may want to perform the following checks with the cruise module unplugged…
1) Do you have 12v + voltage coming into pin F at all times the key is on regardless of if the brakes are applied or not and what position the cruise switch is in?
2) Do you have 12v + voltage coming into pin A with the cruise switch in the ON, RES/ACC, and SET/COAST positions with the key on? (NOTE: when cruise switches start to fail, they may drop voltage on this circuit when you press the RES/ACC and SET/COAST buttons and this will cause the cruise control to become inoperable).
3) Do you have 12v + voltage coming into pin B ONLY when you press the Set/Coast button with the key on?
4) Do you have 12v + voltage coming into pin C ONLY when you press the RES/ACC button with the key on?
5) Do you have 12v + voltage coming into pin D any time the key is on except when the brakes are applied and/or when you step on the clutch pedal; and does this signal drop to ground when you apply the brakes and/or step on the clutch pedal? (Test this circuit using a test light hooked to POS battery voltage so you can verify a good ground with brakes applied and/or clutch pedal depressed – test light should light up brightly NOT dim when it comes on)
6) Do you have good grounds going to pins E and H?
7) Do you have GROUND coming into pin G any time except when you apply the brakes and/or step on the clutch pedal? (Test this circuit using a test light hooked to POS battery voltage so you can verify a good ground with brakes NOT applied and clutch pedal not depressed). Then does this circuit show 12v + voltage with brakes applied and/or when the clutch pedal is depressed?
NOTE: These electronic cruise control modules need to see both brake inputs switch state at the same time (oppositely to each other) when the brakes are applied. They also need to see that the brakes are applied at least once per key cycle before they will start working. This means you simply cannot start the car and take off down the road without touching the brakes and expect the cruise control to work. It needs to see that the brakes were applied at least once after turning the key on / starting the engine before it will enable cruise operation.
These electronic cruise control modules will only work above a certain vehicle speed (usually 35mph). If you try setting the cruise at slower speeds, the unit will not function.
The tension/slop on the cruise control cable hookup to the throttle body must be properly set or the cruise control may not function. There can be some but very little slop with closed throttle, but there should not be tension on the cable with closed throttle that could prevent the throttle from closing all of the way. Excessive slop can result in the system being inoperable.
Let me know if you have problems.
-ryan
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6+ years on this same swap -- NO engine or transmission failures...
Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com
