The tach isn't working at all.  Where do I start?

86 Civic SI, 100% stock, no mods, rust free, owned by little old lady.

A couple years ago the tach would bounce around on the freeway and act crazy, but then it just.... stopped entirely.  Car still runs fine.   Not sure where to start.

You can see the car for a couple seconds in this video:

Ok, through random googling I found out this may be a sign of a failing ignitor module.   I pulled the distributor, and sho'nuff, the ignitor module is out of spec, continuity is not showing up at all between the A/B posts.   So.... off to find one fo those and see if it cures the problem.  It was behaving erratically, not just cutting in and out, but flopping all over the place when it was failing, so I'm guessing this one is donezo.

Second question:  My car is overheating.   I have drained the radiator and swapped out the temp sensor, but it still didn't help so I wired the sensor together so the radiator fan runs whenever the car is on.  It's still overheating.   

Could the radiator just be an old piece of shit/clogged?

Update!   Picked up a new ignitor since mine tested bad...  for a Prelude 2.0, found on Ebay for $17.   Good news is it works, car runs fine, so it's official, Prelude 2.0 ignitors are Civic Si/CRX si Ignitors, and WAY cheaper.

That said.... still no tach movement.   Dammit.  

What are the next steps?  Pull the cluster?   I don't know where I will find another one.

I just replaced an ignitor module because of this thread and still no tach whatsoever.

Update:  Used a meter set to the HZ setting on the blue wire coming into the cluster, bigger connector, just right of center.   Was reading 50-60 hz and would go up/respond when I hit the throttle, so I would assume up to this point anyway, wiring is good.

Disassembled the cluster, see no visual signs of leaking caps/bad solder joints, so I guess I'm just lost.  Even traced teh traces with the meter and the signal is getting into the tach, it's just not doing anything.   

So I checked ebay, yeah, a few clusters, but some of them have WHITE graphics over a black background, but my OEM cluster has orange/amber graphics over a black background.  Other than that they look identical.   What's the difference between white and amber?

Really wish the photos worked in this, anyone have any photos of the different clusters?

Mine is a POS.   Lower miles the better.   Clear plastic can have flaws, I have a good one

Anyone have a ratty seat in their basement with a torn cover and good foam?  Or how about a set of seats with a roach driver's seat and a pristine passenger seat sitting around never to be sold?

I am in desperate need of a seat foam and back for an 86 Si, but I think a CRX would work, and honestly a non SI foam would be fine too.  Please let me know!  I wasted half a vacation day going to 3 different junkyards and came up 100% empty.

God dammit.  New cluster came in.  STILL no tach.

So I've replaced the ignitor, it seems like the lead on the harness is providing a signal... wtfffff

Enjoy, I'm doing a mini series fixing some small things on this.

I've wiggled the instrument harness, and all the harness under the hood, 100% dead, either cluster.   Driving me insane.  

Everything else is stripped.

Episode 2 of my 86 Civic Si project just dropped; trying to fix my broken tachometer! In this video I pull the distributor, test the ignitor module with a meter, find a new one for a prelude for cheap, install that, and my tach is still 100% dead. Would appreciate any advice! 

I do not have a signal generator, so I don't know how to do that.   I have the manuals, is there a section about testing clusters?   Must have missed it; going to go check right now.

Second video on no tach issue:  Removed cluster, tested the harness (I think this looks right?!?), disassembled the cluster to look for obvious signs of electrical carnage, and then installed a junkyard cluster....  STILL NO TACH AT ALL.     

WTFFFFFF

ALSO:  I just used a meter to test continuity between the harness that plugs into the coil, and the harness that goes into the back of the cluster.   Seems mint.   

I'm thinking maybe an entirely new distributor, idk what else to do.

Is there anyplace that sells distributors besides Cardone??

This car is for sale soon.  This website is dead, all the facebook groups are hopeless and pretty much inactive, finding parts has been completely obnoxious.

I like the chassis but fuck this I am trying so hard and getting absolutely nowhere, and the giant void of accessible info and lack of parts has ruined any joy I had for this thing.

I know you changed the ICM but did you change the distributor?  Is it possible that the pickup or some other part is not functional or functioning correctly inside?

I would see if you can get one and try it and if it doesn’t fix it return it.  I don’t have a spare to share or I would.

Episode #4:   Replacing the entire distributor, another $100 down the drain, tach still 100% dead.

this sites user vol died when reddit facebook took over several years ago.

after 34-35 yrs, were getting weird things happening. i like your troubleshooting techniques/skill/videos. and would hope you would keep with it. you can see the unique challenges owning these cars. makes it tat much more special to own and drive around.

what u did makes sense to me. from my experience on these cars, the igniter fails, car doesn’t start. i assume a rebuilt dizzy is a new igniter, bearing and vacuum advance. not sure if a new dizzy is the answer either.

consider testing the tach signal at ur 90si and compare.

back in the factory line days, we’d use 10x jewelers glasses in the engineering lab to look over the components and solder joints. you’d be amazed what information that gives you. swapping the clusters should have solved it

consider searching other 80’s acura and honda models for jumpy or dead tac. someone’s had this and solved it. i don’t recall this posted before on this site

i hope you stay with it. ur methods r solid, i’d hate to loose ur talent supporting this sites repair database

When I first bought this car, this website was not functional for over 6 months.   It just plain didn't work.  FB is useless, as archiving data is impossible, it's just a flash in the pan then gone forever.  

I would have loved to purchase a brand new distributor, but nobody fucking makes them.  Honda sold over 700,000 3g civics here in the states, yet NOBODY sells rebuild distributors.  Mind boggling.  All are just send in yours to be rebuilt.

That said, glad I didn't, as even replacing the entire distributor did not fix the problem.  

The only other thing I can think of is the coil, so I ordered a NOS coil.  I do NOT have continuity across my coil, on the blue signal wire.   I'm not sure if there is supposed to be, but idk what else to do. 

VICTORY IS MINE!

Smash that like button purely because that is a legit screenshot of Sir Mixalot's booty dancer with 3g Tachometers photoshopped on her booty

Anyway, FINALLY FIXED MY TACH! And... if you want to see way too much detail between an Si cluster vs a Non Si cluster, the amount of differences is just staggering; literally no parts interchange other than light bulbs! As a product designer this makes no sense, seperate tooling for even the gauge FACES of the Si, different base, different gears on the speedo, entirely different ways of doing the trip odometer, just... wtf... lol. Kind of a boring video but I was just perplexed at how different these clusters are!

If you have one please PM me

This should apply to any 3g civic/crx/accord/prelude, etc

Wanna learn how to fix your janky ass worn out fart cushions? I'll show you how to restore the seats in your civic for CHEAP! Minimal cost, bit of labor, but pretty easy stuff! Enjoy 🤙

I suppose the extra paint on the radiator could be adversely affecting things. I do know from past experience with my rex, that the process you use when refilling the system after rebuild can directly affect things. I found that using the procedure listed below (which is from another member post here...sorry, if I could remember whos' I'd give you credit!) made all the difference in the temperature on my car...maybe it will help?

 

 

Put a short piece of clear tubing over the air bleed screw so that the tube is higher than the radiator cap. Crack open the bleeder screw until the tubing fills with fluid and watch for bubbles coming out of the tubing. Leave the bleeder screw open, as the tubing will prevent you from leaking coolant.... it will seek it's own level. Jack up the right front corner slightly to tilt the head up towards the bleeder screw. Set your heater on full heat. This will open the coolant lines to the heater core.

Remove the cap and fill the radiator to just below the seat (where the base of the cap seals). Fill your overflow so that it is between the MIN and MAX lines on the bottle. Gently give all of the hoses a gentle squeeze to 'burp' the air out of the system. Top up as needed. Now start the engine with the cap open and the bleeder open. Continue to squeeze the hoses with the engine running until you don't see any more air burp out the radiator, or see any air bubbles coming out the air bleed. After about 60-90 seconds, close the bleeder screw and replace the cap. Allow the warm up fully or take it for a short 5 minute drive around the block until the fan kicks on at least twice. Park the car and allow it to cool fully. When completely cold to the touch, remove the cap and give the hoses a couple of squeezes to confirm the air is removed. Top up the radiator (if needed) and top up the overflow (again if needed).

Top hose hot/bottom hose cold = clogged rad.
Engine overheating/top hose cold = faulty thermostat.

 

This should be stickied, just sayin'.  Awesome writeup, thank you!