C4 Spedo not working after new stereo install?
01-18-2018, 03:14 PM
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3rd Gear
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C4 Spedo not working after new stereo install?
Howdy, owner of a 94 corvette here. Recently I had a friend install a jvc head unit, some subs and an amp. Sounds great, but after he was done my speedometer stopped working. Rather than display 0, it simply flashes random numbers while I’m driving. He cut the factory harness and ran power from the battery to the amp but that’s all. Does anyone know what the problem could be? Any help is greatly appreciated.
-Tyler
-Tyler
01-18-2018, 04:45 PM
#2
Le Mans Master
Gotta love radio experts. Do you have factory wiring diagram? What was original radio? The control head has a data circuit which if connected to radio could be cause. Possibly chaffed wire under car. You need to review what was done during install.
01-18-2018, 05:04 PM
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Thanks for the reply. Wiring diagrams here: http://s716.photobucket.com/user/c4f...?sort=3&page=1 and it had a Delco Bose gold head. I haven’t done much checking wires because I don’t know where the wires to the cluster are but I’ll try to figure that out.
01-19-2018, 12:50 PM
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Ask him what he did with the green/wht wire. He should have just left it not connected to anything. The grn/wht is the Speed signal that goes to several components like HVAC, cluster, CCM, and the radio uses it for SCV. Speed Controlled Volume. If he grounded it, or connected it to something, this could be your problem with the speedo.
You'll probably start getting "SYS" flashing periodically in the odometer too. SYS indicates trouble codes have set in the CCM. There are two codes associated with the backlighting and LED lighting that will set when the stock radio head is removed. There are resistor work-arounds for this problem. If he's going back in the dash to fix the speedo, might as well have him fix the CCM codes too.
You'll probably start getting "SYS" flashing periodically in the odometer too. SYS indicates trouble codes have set in the CCM. There are two codes associated with the backlighting and LED lighting that will set when the stock radio head is removed. There are resistor work-arounds for this problem. If he's going back in the dash to fix the speedo, might as well have him fix the CCM codes too.
Pulled it apart and put a wire nut on the gen/wht wire just now and that fixed it. I do have the blinking sys message, I’ll have to fix that another day. Thanks for the help!