Dead spot in speedometer, tach low
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Joined: Feb 2018
Posts: 94
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From: Smyrna, GA
Dead spot in speedometer, tach low
I have an interesting problem where my speedometer and tach recently became intermittent. Sometimes they would work but read low, other times they didn’t work at all. Now, the tach seems to consistently read about 200 rpm’s low. The speedo acts normally to 25 mph, then stalls out until reaching about 35 mph, then continues rising normally but 10 mph slow. Also, the airbag light is flashing. The pfc reads the speed and rpms consistently and accurately.
I’ve checked the grounds at the uim and the metal bracket by the computer and get 0 ohms resistance. I don’t suspect it to be the speed sensor on the transmission as the pfc reads correctly.
The caps were replaced several months ago in the cluster and everything functioned normally. I replaced the em harness, vacuum lines, and installed the ign 1a coils last week. Initially, the speedo and tach functioned normally after install. This problem started about 2 days ago.
Is there another ground I need to look at? I’ve checked and reconnected the harness connector under the passenger footwell too.
I’ve checked the grounds at the uim and the metal bracket by the computer and get 0 ohms resistance. I don’t suspect it to be the speed sensor on the transmission as the pfc reads correctly.
The caps were replaced several months ago in the cluster and everything functioned normally. I replaced the em harness, vacuum lines, and installed the ign 1a coils last week. Initially, the speedo and tach functioned normally after install. This problem started about 2 days ago.
Is there another ground I need to look at? I’ve checked and reconnected the harness connector under the passenger footwell too.
Thread Starter
Full Member
Joined: Feb 2018
Posts: 94
Likes: 9
From: Smyrna, GA
TThat may be my next option. I have a feeling that it’s one of the ic’s that’s having problems. I just bought another cluster from a 93 manual just in case this doesn’t fix it.
Also, further troubleshooting shows that those gauges don’t work at all when they’re cold. If I leave the car outside for awhile they start working again with the above issues. I resoldered all the through hole connections but that didn’t fix it either.
Also, further troubleshooting shows that those gauges don’t work at all when they’re cold. If I leave the car outside for awhile they start working again with the above issues. I resoldered all the through hole connections but that didn’t fix it either.
Last edited by Alchemyst6; Oct 10, 2018 at 09:24 AM.
Good plan. I went thru 3 clusters before throwing in the towel. I had something going on where the cluster would initially work but would then fail. My initial symptom was an incorrect tach reading and then this manifested into incorrect readings on all the gauges.
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