How long does your glow plug light stay on? (1 Viewer)

[OM617YOTA]

1996 KZJ95

My glow plug light stays on the same amount of time whether ambient and engine temp is 40c or 0c, maybe 2-3 seconds. Under 0c, the engine starts and runs rough for a couple seconds before all four cylinders start firing. This morning, just under 0c, I cycled the glow plugs once before starting, standing outside and waiting until I heard the relay in the engine compartment click off(maybe another three seconds after the light turned off). Turned the key off, turned it back on, waited for the glow plug light to turn off this time, then started. It cranked up just fine, firing on all four cylinders immediately. 0c should not be considered a cold start, it should start fine at that temp.

Temperature gauge works fine, temperature in the info doohickey on top of the dash seems to be accurate.

Is this normal, or should the glow plug light be staying on longer? I'm aware the plugs will stay on even after the light turns off.

 

[KiwiBogan]

I didn't think the glow plug light was an indicator of how long the glow plugs are active for. More just a reminder to let them glow a bit before starting? I never used to look at the light but would just count from 7 to 10 seconds before cranking depending on how cold it was and that was only in single digit temps, not 0°c or less. All 3 of my 1KZ-TE engines behaved similar (even the rebuilt engine) from a cold start, and it went something like this:

0 second pre glow - engine cranks but won't start

5 second pre glow - engine cranks a bit then starts but not a smooth start

7 second pre glow - engine cranks 1 turn then starts fine

10 second pre glow - engine starts perfectly after half of a crank

I also read somewhere once the glow plugs remain on for some time until the engine is up to a specific temp? I haven't tested that theory but always believed that was the case.