Offroad-Express

About 4 months ago my speedo stopped working. At the time I wasn't bothered but I'm now getting close to needing a new WOF so need to get it going again.
Google suggested the problem would lie in either the sender unit or the PCB on the speedo itself.
The Aussie surf site suggested the speedo would be the culprit so that's where I started. The 10uf cap on the right was clearly blown so I replaced it with what I think is an equal replacement.

http://www.jaycar.co.nz/productView.asp?ID=RE6070

BEFORE:


AFTER:


Problem is the speedo still doesn't work
From what I can see all other components APPEAR to be in good condition.
1 track on the PCB looks slightly worse for wear but I've checked it for continuity and it's still ok.

So, any ideas on what could be wrong or where to check next???

the speedo is driven off the ECU . which receives a signal from the speed sensor on the transfer case .

Have you checked the wiring has no breaks / shorts ?
I would borrow an ECU and Custer to check your loom / sender .

the speedo is well known for dry joints and corrosion.
mine stops working now and then, only on cold mornings. soon as it warms up it starts working.

was the odometer working? (or the trip meter).
if either is working then the problem is the gauge not the sender.

Both speedo and odo were working and both stopped at the same time.
I figure the sender unit is fine as I've read of faulty senders causing crap running.
Mine is still running fine even when I had the entire cluster out of the truck. (no CEL, OD still working, engine running the same as ever)
So the ECU must be getting the signal it requires and either there is a break in the wiring between the ECU and cluster or some other compenent is blown or there's a dry joint in the cluster.

FUN...

got a photo of the solder side of the board?

tweake wrote:got a photo of the solder side of the board?

I don't but can take one.
Apart from one track it's in good condition and all tracks check out ok for continuity.

I'm leaning toward the speedo itself being damaged somewhere other than the blown cap.

The voltage across the screws GND and +VE was 13.9v @ idle.
Voltage across the 4P and S screws alternated between 0.18 and 2 when idling forward.

It's looks to be missing a jumper from what I remember of mine.

It must have fallen off!

Got it. Edited.

She's fixed
Turns out it was a blown IC and the board was apparently not repairable.
$300 later
At least it'll get a WOF now....