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| CFI-EFI | Digi Dash Tachometers & Repair | ||
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Senior Guru
 
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As most have probably noticed the tach in the digi dash (1984 - 1989) leaves a lot to be desired. It is slow, it lags, and it can't keep up. Does anyone have or know of someone that has a cure? Is there a way to move, remove, or substitute some resistors? Different transistor(s)? Etc?
Besides my slow tach, my speedo would go nuts for a few seconds, once in a while after I hit a bump. The tach worsened to where besides lagging started producing nonsense in the upper ranges. A couple of times I have blown the 3 amp "Inst lmps" fuse that protects the 4 bulbs that illuminate the panel, only when the headlights are on. The fuse has blown twice and only at the track. With malfunctions adding up, I took the unit to a local repair outfit that has had success in fixing these things by checking and correcting bad connections. He said he didn't see any problems with mine, but that he re flowed the solder on some of the joints that looked questionable. Now the dash doesn't work at all. I am looking for someone that not only can repair it but also improve it. I know I am not the first. Does anyone have any recommendations? RACE ON!!! |
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Posted on: 2009/5/28 15:04
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| CentralCoaster | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
 
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I can answer your question with more questions for someone else.
Is the slowness related to the slow computer? Would an ECM upgrade help? Has anyone even upgraded the crossfire ECM to the faster unit? I also wonder if the problems in the upper rpm could be related to the tach filter (if you have one) or the distributor. Sometimes my tach sort of stalls at higher rpm, but it doesn't go haywire. Typically though, cross-fire (pun intended) in the ignition causes the guages to go screwy anytime the car is running, at any rpm. Anyhow, I think even a fast digital guage would be still be useless for anything but normal driving, and your 84 guages are even less clear to read at a glance. For racing, a shift light is precisely what's needed and nothing more. I use that on the roadcourse and dragstrip and don't look at anything else aside from the oil and water temp guages. Assuming your tach filter and distributor are working fine, you can just tap a shiftlight into the tach wire and still hide it cleanly in the vent to keep the car looking stock. For normal driving, I just look at the numbers. I did however redo my dash color gel so the tach bar turns from blue to white at 3500 rpms and to red at 4500 rpms. So I guess that helps a little bit. |
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Posted on: 2009/5/28 17:41
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1985 Z51, ZF6 |
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| joeld | Re: Digi Dash Tachometers & Repair | ||
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This is a fairly decent article on some dash repairs. Might help ya?
http://www.corvettemagazine.com/1999/dec99/dash/dashp1.asp Joel |
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Posted on: 2009/5/28 17:56
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1989 Coupe,L98 automatic |
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| Matatk | Re: Digi Dash Tachometers & Repair | ||
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Webmaster
 
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That's a good article. For some reason the link on the page doesn't work to continue, so you can use this link to get to page 2 and farther: http://www.corvettemagazine.com/1999/dec99/dash/dashp1.asp That along with the batee site should be everything you need to work on the dash yourself. Matthew |
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Posted on: 2009/5/28 20:53
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| CFI-EFI | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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Quote:
Thank you both of you. The second, corrected URL looks a lot like the original where the "continue" button doesn't work. When I wanted to continue I altered the URL in the address box of my browser by changing the "1" just before ".asp" to a "2". Page two appeared and the continue button worked on all the subsequent pages. Unfortunately, I had already done everything in that article before I let the "expert" fix my solder joints. I will proceed to check out Batee. Thanks for your help. RACE ON!!! |
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Posted on: 2009/5/29 15:10
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| CFI-EFI | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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I don't know that a faster ECM would improve the the tach. This is a common complaint from digi dash owners of all years. I think the tach signals are processed in the dash and not the ECM for display purposes. There are ECM conversions done to the Crossfire to the TBI pick up truck computers that are easier to change the programming on. A few years back when I broke one of the wires off of my tach filter, I bypassed the filter. It has worked great until just recently. The distributor seems to be fine. The goofy, infrequent speedometer reading seem do come only after a fairly hard bump. It reads "288" as if all of the elements of the LCD display are activated. The tach seems fine until over 5000 rpms. Then it displays nonsense, random numbers. The causes and the effects are both different for the tach and the speedo. They appear to be unrelated. I have no problems with any of the other readouts. A shift light would definitely solve the one issue, but I would still like to monitor my engine speed. Do you know of an economical shift light? Wasn't there a Corvette owner building them as a sideline? Your colors and gels are way beyond me. Thanks, and... RACE ON!!! |
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Posted on: 2009/5/29 15:32
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| BillH | Re: Digi Dash Tachometers & Repair | ||
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What do you want to spend? Self contained ones from Autometer or Stewart Warner are $135. Summit has a cheapo with a dial thet's used to set it for $33 (accuracy?). And a digital for $72. |
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Posted on: 2009/5/29 15:47
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Every man dies but not every man lives. |
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| CentralCoaster | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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I wasn't going for economy so much as reliability and small size.
I ended up with a Raptor. It had a good reputation even though it seems like the guy is making them out of his garage, but I guess that's good for quality control. They don't require pills to adjust, and are very small and fit in the vent. I paid extra for the blue light, but I recall the reds were something around $110 assuming he still makes them. There's some photos on my cardomain site below. One limitation of the digidash speed is the LCDs themselves, they simply don't react quickly. I suspect if the tach signal isn't clean, it's more difficult to read as the rpms increase. My car doesn't ever see 5,000 rpms unless I miss a shift. |
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Posted on: 2009/5/29 16:03
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1985 Z51, ZF6 |
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| BillH | Re: Digi Dash Tachometers & Repair | ||
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The Stig Moderator
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I'm used to multiple lights is an aux. dash with laptiming,etc.
These look nice. http://www.ecliptech-us.com/index.php ... &category_id=2&Itemid=116 |
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Posted on: 2009/5/29 16:31
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Every man dies but not every man lives. |
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| CFI-EFI | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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As little as possible for a decent visible light. Thanks for the references. I hadn't none any shopping, at all. Quote:
I will look into the Raptor also. I like the idea of placing it in the A/C vent where it isn't noticeable. I would also want an on/off switch for daily driving. I have been shifting at 6000 rpms, sometimes 6200. I think the valve float, flat cam, and clicking lifters, are the reason I've lowered my shift point to closer to 5600. I like to be able to read engine temp and rpms when racing. I am headed for the track shortly. I hate "flying blind". Thanks guys. RACE ON!!! |
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Posted on: 2009/5/29 18:10
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| BillH | Re: Digi Dash Tachometers & Repair | ||
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The Stig Moderator
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None that I mentioned above are small enough for the vent.
An on/off is easy of course, batt.+, but unless you run to 5600 when daily driving, the lite won't come on. One other way is possible using a RPM activated switch like Summit, SUM-830450, $43, or a MSD switch with pill and one or more 12v LEDs from Radio Shack. |
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Posted on: 2009/5/29 18:51
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Every man dies but not every man lives. |
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| CentralCoaster | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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Do you hit your redline during daily driving? It wouldn't go off other than the light test when you turn the key on. You can close the vent if you don't like that. I didn't wire a switch, but I did use a phone jack connector to power it, and it plugs in next to my Valentine1 under the dash. They give you covers for it, but obviously that doesn't help if it's inside the vent. As for shifting, you always want to set it shy of where you want to shift at to account for your reaction time. A 6000 rpm shift point will result in a 6200 rpm shift in 1st gear, 6150 in 2nd gear, 6100 in 3rd gear... if you get my drift. I think a shift light is absolutely critical for bracket racing if you're shifting manually. There's no other way to shift consistently. |
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Posted on: 2009/5/29 18:59
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1985 Z51, ZF6 |
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| BillH | Re: Digi Dash Tachometers & Repair | ||
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The Stig Moderator
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I have this one laying down in the shop, 3 stage.
Attach file:  IMGP0493.jpg (0.00 KB) |
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Posted on: 2009/5/29 23:01
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Every man dies but not every man lives. |
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| CFI-EFI | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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Thanks for the help guys. Obviously I hadn't thought out the situation when I mentioned the switch. I agree a shift light is a valuable asset. I have just never used one. I'll be looking for dash repair info and vendors as well as shift lights. Thanks for the feed back and info.
RACE ON!!! |
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Posted on: 2009/5/30 17:17
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| BillH | Re: Digi Dash Tachometers & Repair | ||
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The Stig Moderator
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If you go the inexpensive route with a rpm switch & LEDs, here's a pic of a Radio Shack led. It's bright out in the open with the glare, would be brighter in the vent and you could install as many as you want. This one's 1/8th inch, they have bigger ones. Cost about $2.
Attach file: IMGP0494.jpg (0.00 KB) |
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Posted on: 2009/5/30 21:13
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Every man dies but not every man lives. |
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| Flashman | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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Hello, I have been down that digital dash route before. If your digital dash is ok then check the tach wire plug that goes to the distributor, there is also a plug behind the distributor that plugs into a tach filter. If it its loose your speedo and tach will be erratic. Also, remove the cap from the coil on the distributor and make sure the two wires are not grounding out to the metal frame on the coil. Also, check your ground wires. You have one on the steering column, one at each kick panel, and one on the top of the halo post. If you ever have problems with your 84-89 digital dash, I know a guy that repairs them very reasonable. His name is Gary and hes located in Texas. Hes on ebay and his user name is scarabexc. Hes has replaced the LCDs on both of my digital dashes. BTW, keep the sun from beating on that dash cluster or your LCDs will get sun faded. Good Luck. Joe Flash |
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Posted on: 2009/6/2 0:46
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| dan0617 | Re: Digi Dash Tachometers & Repair | ||
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Senior Guru
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I can't say much about shift lights as I set my governor up to do the shifting work for me.
I do know that datalogs show a reading that keeps up much better than the digi dash tach, but even it lags behind. When I'm accelerating at WOT in 1st gear, my dash will read about 5600, then it shifts, then I see 6400 or more. Don't get the last reading till AFTER the shift! I wish it kept up better. On slow to moderate accel. it works fine. Speaking of an '89 here so I'm not familiar with your setup on your year of car, but the speedo problem sounds like a loose wire or contaminated connection at the vehicle speed sensor. Maybe pull the plug at the vss, clean it up, and put some di-electric grease on it. Worth a try. |
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Posted on: 2009/6/2 12:53
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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