Odometer stuck on zero.

[James Brown]

Hi all,

Looking for advice on which part  needs attention/ replacing.

Engine warning light is on & odometer is not moving from zero. Then whilst driving, revs will drop then surge for split second & warning light goes off & odometer will register for a short period then back to zero with warning light.

Any ideas please.

[Picasso]

Hello James have you had the engine codes read by diagnostic this is the first thing that needs to be done .

[James Brown]

Hi lee,

Taking to garage, will advise when done.

Initially thought that someone would recognise this fault.

[Picasso]

It could be a number of things my best guess would be speed sensor on gear box there is 2 fitted 

[James Brown]

Thanks Lee. 

[James Brown]

On 6/16/2025 at 4:24 PM, James Brown said:

Thanks Lee. 

Hi again Lee,

Looks like you may be right about the speed censors.

The auto electrician needs a wiring diagram as he says the 2 wires do not go straight to the speedo head.

Is one available on the Forum?

Also, part numbers for the 2 speed censors & recommended supplier, Toyota are quoting £168 + vat each.

Thanks in advance for any help.   

[Picasso]

hello james i have sent you a private message

[James Brown]

Many thanks for that advice.

Does the speed sensor wiring go direct to speedo / odometer head or other ?

[Picasso]

sorry that i dont know 

[smurf]

The speed sensor will go through an ECU. There will be a canbus connection to the dash from the various ECUs, which brings me to my question. How has your car been converted to read mph? Has it had a dash overlay, or has it had a canbus chip installed? The canbus chips can cause all sorts of issues when they play up. If you aren't sure, an overlay will likely have mph and kph numbers on, but if a canbus chip has been used it will be just a single scale. 

[James Brown]

Hi Richard,

Many thanks for your impute.

It has a chip to convert to mph. The auto electrician checked that says that it's not the chip.

I showed him the transmission speed sensor info that lee sent & he says that I probably won't need them as it's likely to be the gear box sensor & he needs a wiring diagram to investigate as he's not familiar with the 2 wire system. I can't find any info re a wiring diagram on the Forum, can you point me in the right direction to get one?

I'm completely in the dark about these things I'm afraid! 

[smurf]

I've sent you a PM James, with some info about a manual. 

[James Brown]

On 7/18/2025 at 6:37 PM, smurf said:

The speed sensor will go through an ECU. There will be a canbus connection to the dash from the various ECUs, which brings me to my question. How has your car been converted to read mph? Has it had a dash overlay, or has it had a canbus chip installed? The canbus chips can cause all sorts of issues when they play up. If you aren't sure, an overlay will likely have mph and kph numbers on, but if a canbus chip has been used it will be just a single scale. 

 

[James Brown]

Received this from electrician.

It’s not a can bus system on your vehicle. it’s a simple square wave signal in a dedicated speed signal input but the issue is where that comes from the cluster then sends a speed pulse to the engine ecu

There talking about a later model that has a can data driven speed signal 

[smurf]

What year is your car?

[James Brown]

2007   2.4L

[smurf]

I assume the electrician has not looked at the schematics, and is only considering the implementation of canbus in its most modern form where nearly everything on a car is directly on the canbus.

 

A 2007 Alphard has canbus and MCX to the dash. The schematic in the manual appears shows the speed signal to the dash is provided over canbus. The sensor is not connected to canbus, it is connected to one of the ECMs that will have a canbus connection. If the electrician has checked the canbus speed chip why do they think the car doesn't have canbus? I'd be disconnecting the canbus chip from the dash and see if the problem goes away. 

 

[James Brown]

The manual was sent after they closed yesterday & he probably hasn't looked at it yet. Can you tell me what page of the manual the above information is on please. As you can gather, I'm totally ignorant about wiring systems & jargon!!