90 Series Auto Diesel Tacho problem (Fixed)

[cavidj Lurker Find all posts View Profile Close cavidj]

Hi all
Thought I would post my experience with an intermittent tacho in my Prado. 6 months ago the tach became intermittent, did'nt do anything about it at the time but as we are about to sell the vehicle I wanted to get it fixed. Local Auto Electricians in Adelaide had not seen this problem before but I was sure it was a dry joint in the cluster. Wriggling the wiring loom and warmer weather seemed to make it come good briefly. It eventually failed altogether, so based on a previous post in this forum I called Peter at Auto & Marine Instruments Moorabbin VIC. He had fixed plenty of Prado instrument clusters before but had not seen this particular fault. All indications showed the tacho was working on the bench so we agreed to resolder unit.

Returned the cluster today and installed, all working puurfectly.

Thanks Peter, great service and I can recommend your work and helpful advice.

Dale

[williade Avid PP Poster! Find all posts View Profile Close williade]

A slightly different experience here. I had an intermittent fault with my tacho when I bought my Prado. I have no idea how the tacho in a Diesel Prado works, but in the early model V6's the igniter produces a square wave that is 3 x RPM on a single wire that is fed directly into the meter. By running a wire directly from the terminal of the meter to an oscilloscope I confirmed that even when the Tacho was reading 0 rpm the signal from the igniter was still reaching instrument cluster. I assumed it was the meter itself that was faulty.

I manged to get a used cluster from eBay and I transplanted the tacho into my dash and that fixed the issue.

The later model 90 series Prados have a digital odometer and an ECU of sorts that controls all the dials so I doubt they would be as easily repaired.