|
1994 SC2 tach suddenly stopped working
Hi folks of Saturn! I have a pretty pristine 1994 SC2 in teal that my folks bought new. Been garaged most of it's life, used as a "dingy" behind a motorhome, only has about 98K miles, and I'm fixing up some minor issues to use it as an "around town" car. Recently fixed the passenger side pop-up headlight mechanism by replacing the nylon gear, had new tires installed, and replaced the original donut spare. No surprise, the odometer isn't working (stopped a couple years ago), and I've already ordered the 2 gears and have read up on how to replace those, but just recently the tach stopped working as well. The speedo and all other gauges and lights work BTW. Just can't seem to find any precise info on the tach, except that it may be a loose connection at the instrument cluster board. If anyone has any other info to offer, I'd appreciate it. Should be pulling the dash and cluster next weekend, and want to make sure I get the tach working before I button it back up.
OOPS! Just noticed this is the SL thread. I won't re-post in the SC thread, just let mods move it if they'd prefer Also will add a couple pics. https://cimg9.ibsrv.net/gimg/www.sat...38633ba616.jpg https://cimg1.ibsrv.net/gimg/www.sat...dbf189b064.jpg |
I LOVE THAT TEAL
Haven't read your post yet----just had to throw that in |
Be Gentle with the top dash cover. 25 yr old dry rotted plastic is extremely brittle. Yours has not seen the # of heat cycles as most that age but nonetheless, plastic of this type dries out and gets brittle. Be sure you only pull up on it with an upholstery clip tool and only where the connectors are. You can distort the shape otherwise. It doesn't take much to matter because a small distortion in the middle or at one end adds up to being much further off 3 ft away than you'd think. More likely to snap in your case.
BE GENTLE with the connector to the instrument panel, especially if you have never ever ever disconnected it. It has 25 years of oxidation and corrosion built up, and because there are so many pins, it often seems glued in place/solid when you go to disconnect the harness. Deal with the connector removal before setting the IP free (unmounted) or you have no way to keep the IP still. The working quarters are tight and may require someone with strong small hands. Work around the entire connector so you remove it evenly. If you get it off-kilter (uneven removal), it makes it that much harder and puts lateral stress on everything. Use a high-quality electrical contact cleaner during diag and before reassembly. The following describes the pertinent portion of the IP circuitry. The devices are of course in parallel as they share the IGN1 power feed. The following is quoted from a 1991 -1993 Chilton Manual. I have found the wiring diagrams in this book to apply through 95 and mostly to 97. 99/00 got the BCM so no good after that. TACH AND SPEEDO The tach gets its power feed through a PIK/BLK wire which runs into the harness connector. This is a feed on the IGN1 fused circuit. This is the same power feed that, on the IP, goes to the speedo and the electronics that drive the speedo and odo. The speedo and odo have their own electronics control on the IP. The tach has a separate electronics control on the IP. The input signal to the tach comes into the harness as a WHT wire. Since your speedo works (and all the other gauges, we know you are getting the IGN1 feed through to the speedo electronics and the speedo itself and presumably the ground for the electronics control for the speedo/odo is good -- will describe grounding later (Aside: Since the odo's can fail electrically-----might as well describe the odo circuitry -- not a whole lot added.......) The odo and trip odo receive two separate signals from the speedo odo electronics on the IP in addition to the IGN1 power feed GROUNDING The grounds for the Speedo odo electronics Speedo odo iteself Tach electronics share a ground path on the IP, but there are 2 pins for these grounds as they leave the IP back into the harness - one is depicted as a ground for the speedo odo trip odo the other is a cluster ground ON THE IP ITSELF where all the device grounds come together before leaving the IP--this includes the ground from the tach electronics Note that the speedo odo is redundantly grounded through both ground paths more than once. The two ground pins that leave the IP are run to the same ground splice pack EXTERNAL TO THE IP. ---------- DIAG ORDER 0) BEFORE you replace all the bulbs, address the tach issue. Logic: you want to do this without the bulbs in, as banging them around will decrease their life expectancy. One could argue that doesn't matter. Just sayin' 0.5) After removing the connector and spraying the contact cleaner, "sweep" the contacts free of corrosion/etc by carefully working the connector on and off. This is a PITA based on its location but is the most likely source of your issue and also the easiest to fix. Test by starting the car with the dash connected. Either it works or it does not. If it does not: 1) Check to see if tach is getting the ign 1 feed ---check at the input to the tach (on the IP board) 2) Check to see if the tach electronics are getting the IGN1 feed --check input at the tach electronics module on the IP board 3) Check the ground at the exit of the tach electronics to ensure it is connected to the onboard IP cluster ground 4) I would normally say to check the ground exiting the IP to ensure it is actually properly grounded at the splice pack, but since everything else on the IP works as it should, this is likely not the issue. Given its age, cold solder joints are not out of the question, but we'll go there only if we have toi...... As far as tracing the circuitry on the IP.... I don't know which modules are where on the board. I also don't know if there are ground traces or a ground plane in the center of the board. If you post a pic after ]you pull it I will try to help at the board level if needed, but no guarantees. Pls keep us updated I think Richpin has a video on cluster removal and assembly |
Thank you very much for all the great information and warnings, Derf. I have watched the Richpin video, and another set of videos of disassembling the cluster and replacing the gears:
I have a set of auto trim tools arriving today from Amazon: The gears should be here by Thursday or Friday. However I'm frankly still vacillating a bit between just leaving it be, or fixing the odo and tach. Being an automatic, I really don't need the tach, and the odo would be nice, but since I plan to keep the car, not a huge deal. However it's in such great shape otherwise, I'd like to have her all working. Have plenty of experience mechanically, working in tight spaces, and figuring things out, but also have a good sense on when to say no, to avoid doing harm. So I'll probably think about it some more, watch the videos some more, then move forward, or just wait. Agree about the teal. This car really "pops" on the road. In this town my parents had this one, and there was another teal SC2 we'd see on the road without the spoiler. Both really stood out from the other cars on the road. I recently removed and stored a center consul with armrest they added (or may have been in the package) and it's much more more comfortable to drive now. It was always in the way when I drove it. By removing that I also found the lumbar lever on the right side of the driver's seat back that I didn't know was there, flipped it up, and the seat feels much better. Very fun car, and I'm lucky that they kept it in such great shape! (which is one reason I'm reticent to harm the dash and IP) But thanks again for all the info. I will refer to it when/if I move forward on this, and will post pics as I do so. |
Go for it. Pls do a write up on the odor gears. I have been without a trip odometer for over a decade. No more odometer still works but I would like to get a hold of a set of the gears and how to replace them before the information disappear along with the gears. Sing the video of somebody remove the top dash is critical because then you see exactly where the attachment points are. It's when you start praying in random places that you are likely or much more likely to cause damage or warping. Plus you have a mechanical sense about you and it doesn't sound to me like you would force things as you actually said. Just do it on a warm but not sweltering day and not a freezing day. You wanted to be as generally flexible as possible.
Many have attempted odometer repair and many have succeeded. The key is patience and knowledge. |
By all means. At least you noticed it, did not post in the new member area with a tech question, etc.
I would much rather move but useful post then waste part of my life to leading a double post Oh, you might as well replace all the bulbs while you're in there. The point being there should never be any reason to pull the cluster again when the plastic is even more brittle. Just don't put them in until you are ready to reinstall the cluster |
Originally Posted by derf
(Post 62506)
Go for it. Pls do a write up on the odor gears. I have been without a trip odometer for over a decade. No more odometer still works but I would like to get a hold of a set of the gears and how to replace them before the information disappear along with the gears. Sing the video of somebody remove the top dash is critical because then you see exactly where the attachment points are. It's when you start praying in random places that you are likely or much more likely to cause damage or warping. Plus you have a mechanical sense about you and it doesn't sound to me like you would force things as you actually said. Just do it on a warm but not sweltering day and not a freezing day. You wanted to be as generally flexible as possible.
Many have attempted odometer repair and many have succeeded. The key is patience and knowledge. Well, removing and repairing the pop-up headlight mechanism seemed daunting at first, but with the aid of some write-ups on it, I completed that with no harm done. Total cost: $10 for the gear. Agreed about doing it at the right temperature. Was thinking I need to do it before winter. Temps here in the So Cal beach area are moderate in the summer, and in the garage usually 75-80 these days. Would be the right time to attempt it. Ironically, I was probably the one that caused the odo to stop. Driving my then 92 year old mom to my sister's home and hit the trip button to record the trip's mileage. But it was a failure just waiting to happen, as I've learned that the stock gears were prone to failure because of the petroleum grease used on them compromising the plastic. The new gears are self-lubricating. I'll likely go for it... Ah! The tool kit just showed up, could have used some of these doing work on my truck recently. I keep seeing folks using screwdrivers and chisels as pry tools on interiors panels, but for only $9 shipped, I'll play it safe! https://cimg1.ibsrv.net/gimg/www.sat...af696c22e4.jpg |
Got the dash off and cluster out this morning. No issues. However when I removed the cluster the connection was loose and pulled out by itself, so apparently it's never been properly seated. You can see in one of the pics from the top after I removed the dash cover, it's at an angle. So thinking this was what caused the tach to stop, I seated it and started the engine, but still no tach. BTW the three hook legs that secure it are not broken, they just were not engaged well.
I see one white wire at the bottom left of the plug, perhaps the tach. How would I check to see if it's getting signal? Is it variable voltage I'm checking for? The gears are arriving today to I'm going to dissemble the cluster soon using the instructions they have online: http://m.odometergears.com/howto/Sat...eplacement.pdf https://cimg5.ibsrv.net/gimg/www.sat...2aa42fce35.jpg https://cimg2.ibsrv.net/gimg/www.sat...a058e9185d.jpg https://cimg6.ibsrv.net/gimg/www.sat...5ac616580f.jpg |
Got the film off. You can see the three black connectors that have to be carefully pried up to remove it. Just follow the directions on the link I posted above, not too hard. This is the underside:
https://cimg8.ibsrv.net/gimg/www.sat...72431fb0ff.jpg |
Got the housing apart. Not easy, having 10 snaps, and make sure you get ALL the black screws out. I missed 2 on each end, but luckily didn't hurt anything prying before I noticed them. PATIENCE is the key. Also as you work around freeing the tabs, insert a folded business card or similar to keep to gap open as you work on other tabs. Prying the face plate out is easy, just be careful and go slow.
Have the odo pod removed and removed the motor, and yep, the red gear is shot. Funny thing, a minute after I finished this the mailman showed up with the new gears :) So I'll put it all back together, clean up the contacts on those small black connectors that power the odo, tach and speedo, then see if the tach works now. If so, I'll re-install the dash etc. If not, I'll have to troubleshoot some more. https://cimg0.ibsrv.net/gimg/www.sat...764b8a9ebc.jpg https://cimg4.ibsrv.net/gimg/www.sat...b5c2abfe43.jpg https://cimg7.ibsrv.net/gimg/www.sat...0dca517ab6.jpg https://cimg9.ibsrv.net/gimg/www.sat...db26ddb3f0.jpg https://cimg3.ibsrv.net/gimg/www.sat...8af03dbcab.jpg The new gear set: https://cimg5.ibsrv.net/gimg/www.sat...f4acfee646.jpg |
| All times are GMT -5. The time now is 01:40 AM. |
© 2026 MH Sub I, LLC dba Internet Brands
