1998 Prado 1KZ-TE Diesel Knock / Glow Plugs / Glow Plug Relay Timer

[PradoSouti Lurker Find all posts View Profile Close PradoSouti]

Hi,

I have a Prado 1KZ-TE with 200k km on the clock. It started knocking recently so we thought to see if the injectors were needing replacement. They have been refurbished and redone.
So when the vehicle starts its quiet and runs fine, after a few minutes it then starts knocking. So then we checked the glow plug relay and this is working fine. Then we checked the voltage at the glowplug bridge.

So when the vehicles starts there is +12v at the glow plugs and then it runs good. After a few minutes the +12v falls away and then the knocking begins. So the glow plug relay is working fine, where do I look for the timer that runs the relay ?

Could the coolant thermostat not be working correctly ? Although the temperature does increase on the dash.
What controls the glow plug relay ?


Any help would be appreciated.

[carco Advanced Member Find all posts View Profile Close carco]

The ecu controls the glow plug relay, coolant temp is the main input.
Unless you live in Iceland, they don’t need glow plugs.
Once the engine starts, the combustion heat keeps the ceramic tips white hot.
I’d check for any ecu fault codes, sounds more like a timing issue to me.

[PradoSouti Lurker Find all posts View Profile Close PradoSouti]

Hi Carco,

Thanks for the response.

I went ahead and checked the error codes by bridging the E1/TE1 pins on the diagnostic plug.

I have the following codes:

12 - No RPM signal during cranking
13 - No RPM signal after cranking and engine reaches 680 rpm+
14 - Timing control signal (Crankshaft angle 7 deg or more out from target)
24 - Intake Air Temp Sensor
33 - Intake Contrictor control signal

Some more background on the vehicle, my father passed away and it has been standing for +- 2 years only being driven periodically to charge the battery a little and then the terminals would be removed.

Would you suggest still checking the timing first or replacing sensors etc first.

[PradoSouti Lurker Find all posts View Profile Close PradoSouti]

Update:

cleared all the errors and the only error left is 12.
will be checking the crank position sensor wiring and then the sensor itself

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

Rpm signal is from the speed sensor on the fuel injection pump

[SamSta Member Find all posts View Profile Close SamSta]

Interesting read. Tonight I had for the first time since installing a new (2nd hand) engine which has had most external things replaced (head, glow plugs, injectors, turbo etc) a terrible knock (not tap, knock!) at the top of the engine on cold start. Sounded terrible! Went away eventually. Engine is performing excellent otherwise. Went for a decent drive. No dramas. Came back. Parked up for half an hour. Went out again for a drive, no dramas.

A few hours later, decided to go out and check for any DTC codes using my bluetooth dongle and an app which seems to pickup some codes (not sure how accurate it is). Came back with no results. *side note* I've noticed since the new engine install (dodgy mobile mechanic job), the wiring harness seems to be hanging/pulling downward with quite some force pulling tight on all the sensors on the injector pump side of the engine.

Anyways, started the engine and while the engine was idling nicely as it should, I grabbed the bulky part of the wiring harness coming from the firewall and lifted it up taking the slack off the wiring to the sensors. Suddenly the knocking noise started fading back in quietly and felt as if it would get louder if I had held the harness anymore. I gently lowered the harness to where it was resting before and the knocking noise faded away again.

In my situation, there defitnately seems to be a problem with one of the electrical connections - probably to do with the timing on the pump. I've also had a power steering pump leak which has sprayed fluid all around the area so possibly created a dirty electrical connection in the vacinity. Coincidently, when dropping my daughter at school the other day, the car decided not to start. Classic clicking noise when you turn the key with a faulty starter motor. I jiggled the electrical plug connection on the starter motor while my daughter turned the key and the car started straight away. The starter motor connector in question was also sprayed and soiled with power steering fluid.

Anyways, I hope this provides some insight for you as to other things to check for before fearing the worst. I'll try and remember to update my results once I get a chance to have a look in daylight over the next couple of days. But my intuition says their is a broken wire or dirty connector somewhere on one of the main sensors to do with timing and the awful knocking sound is actually just the ECU trying to figure out the timing from a dodgy signal given from one of the sensors.

[PradoSouti Lurker Find all posts View Profile Close PradoSouti]

Rpm signal is from the speed sensor on the fuel injection pump

Thanks, the speed sensor sits on top of the fuel injection pump. If this sensor is plugged out the vehicle does not start. And when I plug it in then it starts fine. The only thing I can see that is odd regarding the wiring, 2 wires go into the sensor and the white wire shares a loop with GND that is bolted on the engine. Not sure if that is correct. If the shared GND is removed the vehicle also does not start.

[carco Advanced Member Find all posts View Profile Close carco]

Have you checked the CAS and it’s wiring?
It’s down the back beside the starter and if you’ve had an engine out or replaced a starter, it can be damaged very easily.

[PradoSouti Lurker Find all posts View Profile Close PradoSouti]

Hi Everyone,

So to update I took off all the sleeving etc and found that the electrical was kinda shoddy and wires were soldered together and extended etc.
I repaired all the wiring and replaced all the connectors for the sensors.

I then moved onto the crank position sensor, its a real mission to access this and removed the wheel and jacked the vehicle up to try and access it.
So when I plugged out the sensor the plug was also old and both wires came out, 1 had its pin on and the other was broken off in the plug.
Repaired the wiring and replaced the plug.

That sorted out the entire issue.

Thanks to everyone for their comments etc, its much appreciated.