ECM code 24 question
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From: Leominster MA
ECM code 24 question
The speedo on my 87 has been intermittent since I got the car 3 years ago, sometimes steady and accurate, sometimes jumps all over the place. It sets a ECM code 24 when it flakes out, SES light comes on for a while then goes out. This season (since March) it has been rock solid, no problems. Had the car in the shop for some work on the climate controls and when I got it back, although the speedo is still working fine, I got a SES light while driving that came on and stayed on. Dumped the ECM and it's code 24 (VSS). Haynes says it could also be ECM failure, which would fit the light staying on and speedo working. Anyone had a similar experience? Does this look like ECM failure? (I may have a bone to pick with a mechanic). :boxing
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From: SE NY
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Re: ECM code 24 question (Spike T)
If you have a speedo cable and mph reads ok but you get code 24, verify pulses getting to the ECM. If pulses, replace the ECM.
If no speedo cable and mph reads ok but code 24 is steady, replace the ECM.
If you need an ECM, give Contemporary Corvette (link on my site) a call on a used one.
[Modified by 65Z01, 12:10 PM 4/25/2002]
If no speedo cable and mph reads ok but code 24 is steady, replace the ECM.
If you need an ECM, give Contemporary Corvette (link on my site) a call on a used one.
[Modified by 65Z01, 12:10 PM 4/25/2002]
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From: Leominster MA
Re: ECM code 24 question (65Z01)
Sounds good; forgive my ignorance, but how do I tell if I have a speedo cable? I was under the impression it was all electronics (VSS in the tranny, signals to the ECM, display on the digi dash) ?? :confused: One more related question: is the analog milage display (upper right corner of the dash) at all driven by the VSS/electronics, or is it truly separate and analog?
Melting Slicks
Joined: Jun 2000
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From: Las Vegas NV
Re: ECM code 24 question (65Z01)
If you have a speedo cable and mph reads ok but you get code 24, verify pulses getting to the ECM. If pulses, replace the ECM.
If no speedo cable and mph reads ok but code 24 is steady, replace the ECM.
If you need an ECM, give Contemporary Corvette (link on my site) a call on a used one.[Modified by 65Z01, 12:10 PM 4/25/2002]
If no speedo cable and mph reads ok but code 24 is steady, replace the ECM.
If you need an ECM, give Contemporary Corvette (link on my site) a call on a used one.[Modified by 65Z01, 12:10 PM 4/25/2002]
Do you happen to know how much they sell a used one for?
A rebuild from a auto part store cost about ~$90-$100, you have to return the core.
I had code 24 VSS before. With Dave-F help to troubleshoot the problem, it turned out to be the ECM. Do a search on the topic code 24 VSS. Dave-F gave a lot of way to test the code 24 at that time for a less than a back yard mechanic like me :rolleyes:. From the way it sound, new ECM is needed:). I remember something about getting the new part number of the ECM. I believed 87 used the old ECM.
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From: Leominster MA
Re: ECM code 24 question (Spike T)
Replaced the ECM this past weekend ($80.00 from AutoZone after $140. core charge). Before changing ECM I would drive almost exactly 2 minutes before the SES light came on (always code 24, speedo working fine). With new ECM it takes about 7 minutes of driving to set the code. That's improvement, I guess. What else could it be?? :confused:
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From: SE NY
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Re: ECM code 24 question (Spike T)
I'm not sure how to check for type of speedo interface. I was relating diagnostic info from John Baechtel's book on TPI Fuel Injection.
I would think that you can check the interface at the tranny to see if a cable or electrical wire comes out.
I would think that you can check the interface at the tranny to see if a cable or electrical wire comes out.
Thread Starter
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Joined: May 2001
Posts: 68
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From: Leominster MA
Re: ECM code 24 question (Spike T)
Replaced the ECM this past weekend ($80.00 from AutoZone after $140. core charge). Before changing ECM I would drive almost exactly 2 minutes before the SES light came on (always code 24, speedo working fine). With new ECM it takes about 7 minutes of driving to set the code. That's improvement, I guess. What else could it be?? :confused:
3rd Gear
Joined: Oct 2004
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Replaced the ECM this past weekend ($80.00 from AutoZone after $140. core charge). Before changing ECM I would drive almost exactly 2 minutes before the SES light came on (always code 24, speedo working fine). With new ECM it takes about 7 minutes of driving to set the code. That's improvement, I guess. What else could it be?? 
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