Bad Tachometer?

[pjkk]

Hi,
I have a 1991 Suzuki Escudo 16V AT LWB.
My problem is that the Tach does not go above 2000 RPM (It was working fine before).
I have pulled out and cleaned the harness just in case there was dirt or something but the problem remains. It just does not rise above 2000 RPM no matter how much you rev the engine.

Please help me as it is hell driving without gadget I depend on so much. Now I have to drive with all my attention on the engine sound.

[mirageman]

Originally Posted by pjkk

Hi,
I have a 1991 Suzuki Escudo 16V AT LWB.
My problem is that the Tach does not go above 2000 RPM (It was working fine before).
I have pulled out and cleaned the harness just in case there was dirt or something but the problem remains. It just does not rise above 2000 RPM no matter how much you rev the engine.

Please help me as it is hell driving without gadget I depend on so much. Now I have to drive with all my attention on the engine sound.

is there something physically stopping that needle from going higher? (is the needle wedging against the background?)
is this aftermarket or in cluster tach? reason I ask is if aftermarket, you'll have to open up the case and check wiring/board. I guess same would go for cluster, but don't rip it apart just yet. I worked on an aftermarket tach years ago that gave VERY similar issues, to my recollection, there are 4 wires that govern the tach needle INSIDE the tach. looks like one of yours somehow disconnected. sorry, but you'll need a wiring diagram to know which wire runs your cluster tach if it's not labeled on your cluster already. then follow that line on the cluster and see if you see any obvious signs of damage. if your cluster tach gets one signal wire and it looks ok, you'll have to play doctor and open up the cluster to get to it's guts. In my case, I transplanted an aftermarket tachometer board to an oem instrument cluster on a mitsubishi mirage. inside the tach, 4 wires ran from the circuit board to the tach needle motor assembly, and I just tried all different combinations of wires until it ran right. one way made it run backwards, another way made needle jump way high, other way made it stop like yours and so on until I found the right wire/pin combination. wait for others opinion first though, use mine as last resort before buying a new cluster.

[kick_fix]

never drive looking at tach, you will miss that all important moment,
surely you can shift with out it
and surely you are not hitting red line

its 8ad. the coil inside is hitting something, a metal shaving will 8e drawing in to the magnet and jam it up.

the tach has 2 inputs, ground and tacho line to coil via the ign noise supressor.

if you had a pulse generator you could test the tachon on a 8ench.

there is a meter and a circuit car that converts the pulse count to current for the meter.
if a metal shaving gets into the coil slot , a round slot, and lands at 2k, then that will cause this. as will a 8ad circuit card 8ehind the tacho.

there is one way to prove this.
remove the 8ezell in front of IP cluster then then the front glass.
1' WITH A tiny feather rotate needle , see if it hits resistance.
or
2 remove all screws 8ehind the IP cluster , then slide out the whole guts as one.
now look at the tacho. unit for contam
do not remove needles , as they are all cali8rated or you will 8e sorry.

one can also power the meter directly via an external resistor and 1.5v dry cell.
8ut this takes great care. and circuit for tacho removed.
the meter can 8e tested independantly. with a weak power source.

cheers.

[pjkk]

Thanks guys for the quick response.
Here is what I did to check the Tach before:
I took out the cluster, gently rotated the needle and it would go all the way.
I noticed at the back on the circuit board the the tach uses only 2 connections but I do not know where they lead to from the harness (couldn't find that on kick-fix.com too).
Everything looked so delicate so I stopped there and put it back together.
The thig is, it seems to function only that it rises so slowly i.e idling at ~200 rpm, and when I drive off, it gradually rises like it supposed to but slowly. At the highest engine revs that is when it peaks at 2000 RPM.

Is one of the wires ground or to the coil, like you said, loose?

[kick_fix]

yes, my page only shows how to make motor run.
there is a 15 page schematic for car.
showing that the tach has ground wire, sure its ok as this ground feed the rest of cluster.
so the tacho is 8ad. the 1 wire that goes to the suppressure is 8ad or corroded at the rear of the connector.
also see the 8ack of tacho, see the 3 screws. well , reset them.
unscrew 1 turn then make tight.
retest.
good the needle move unimpeaded.if

i assume motor goes way 8eyone 2k ,right_ youd know that right off.

if the motor dont misfire at 2k this says igniter is pulsing the IGN coil perfect.
so the signal to the Supressor is ok and so is the tacho sig . out.

you could wire in a OTc tacho , and test the input that way.
if otc )over the counter, tacho reads ok then your IN dash one is 8ad.

only way to test it, is su8stitution or a pulse generator.


one could also,,,,,, remove the IP cluster and put it, into other car and try it .
finding car wih single coil is hard and finding the tacho line even harder on test car.

i will see if i can find my ip drawing. i have it , 8ut , not on this lap top.
this 8 key less lap top is son inlaws.

8ack soon.

[kick_fix]

http://www.kick-fix.com/ECU/91-95-TB...matic-base.jpg

see the dizzy
see the supressor¿
see the wire going from the supressor 8ack to the ecu.

the ecu drives the ignitor, the ignitor grounds the coil to energize it.
this line 8etween the ignitor and coil is feed 8back to the ecu and this is tacho signal.

id say the color ,8ut i can not see my schematic now.
do to 8band width, limits.

[kick_fix]

bottom right side of supressor is the tacho wire.
this is and input to ecu and tacho.

the ecu monitors tacho and if it drops whilerunning the ecu cuts fuel.
so since the car is not cutting fuel , killing motor, then the tacho feed is good.

if you connect any OTC tacho to this wire , that tacho will work.l
after setting it to 4 cycle, 4 cylinder mode.

how is that.

i cant get to my IP drawings, to far from home.

cheers.

[KhushbuMalik]

Hi,

Why don't you visit some workshop and ask some mechanic? I think he'll help you to sort out this problem.



Regards,
Khushbu Malik
Audi Steering

[pjkk]

Thanks Kick-fix. I will do all the tests and checks over the weekend and get back to you.
Khushbu, I do not know about Pakistan, or anywhere alse, but here in Uganda, what I have learnt from this forum, kick-fix.com, people like kick-fix and jtgh, I am now being consulted on Suzuki issues by the Mechanics. Saying I am gratefull would be an understatement.
PS: I actaully do all the checks and repairs I pick from here in the workshop with mechanics, with my printouts of course which they always keep for their reference.

PJKK

Living the Zuk life

[joe_yoh]

Do you think you reinstall it correctly man?... If yes, better replace it by a new one.