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Triker
New User
Jun 29, 2014, 2:39 AM
Post #1 of 5
(1542 views)
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97 Tahoe ground issues.
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New to forum, just did the central SFI to MPFI conversion on my 97Tahoe and now I'm having a tach issue, at idle it is showing 4500 RPM, can anybody on here verify the grounds on the back of the right cylinder head for me, could've sworn there was a ground lead there with a serrated washer swaged to it but I can't find it now.
Also can anybody show me the speedometer buffer module, this was a stolen recovery that I replaced the whole harness from a 98 and the speedometer buffer is off big time.
Thanks in advance.
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Hammer Time
Ultimate Carjunky
/ Moderator
Jun 29, 2014, 3:44 AM
Post #2 of 5
(1525 views)
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Re: 97 Tahoe ground issues.
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The first thing I would do is hook up a bidirectional, professional scan tool and test all the functions of the dash cluster to eliminate that from suspicion. These clusters have a long history of problems.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Jun 29, 2014, 3:57 AM
Post #3 of 5
(1521 views)
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Re: 97 Tahoe ground issues.
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There is no speed buffer module on the gasoline version of the Tahoe for that year. The conversion is done inside the VCM.
The cluster for that year doesn't use a processor to control the gauge, so a scan tool won't help you on that. The tach gets its signal directly from the control side of the ignition coil and the speedometer gets its signal from the vehicle control module.
You can use the scan tool to monitor vehicle speed data and then compare it to the speedometer gauge to see if it is off. I also believe there was a way to alter the programming in the VCM for different tire sizes. Not sure on that though.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jun 29, 2014, 4:08 AM)
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kev2
Veteran
Jun 29, 2014, 7:46 AM
Post #4 of 5
(1512 views)
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Re: 97 Tahoe ground issues.
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some thoughts-
Was everything OK before CSFI to MPFI ?
SCAN yes get a scan even if the CEL is OFF.
Vehicle is STOCK- no aftermarket ?
Describe the speedo problem you said way off - describe 10mph when stopped? @35mph shows 55mph
Does the tach respond to throttle or stuck at 4500rpm
PS - Got to ask why did you put a new harness in and WHY was a 98 harness put into a 97 vehicle?
(This post was edited by kev2 on Jun 29, 2014, 7:55 AM)
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Triker
New User
Jun 30, 2014, 2:04 AM
Post #5 of 5
(1498 views)
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Re: 97 Tahoe ground issues.
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The thieves cut the main harness at the ECM when they pulled out the engine, the harness I got with the engine and trans was a 98, replaced entire harness and dash harness, tach was fine prior to injection conversion, speed has been off the 8 years since I built it, yes all stock.
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