I have a 1999 Toyota Hilux 2,7-litre Raider 4×4 with a diff-lock on the rear axle and manual-locking front hubs. Is it acceptable to drive with the front hubs in the locked position while in 4×2-mode and then select 4×4 from the interior when I need it? It's a hassle to have to get in and out every time I need four-wheel drive.
Recently, the bakkie was parked at an angle on a steep, tarred driveway. When I tried to reverse, one back wheel spun as it was unloaded and had no grip. I then selected the diff-lock on the dashboard and the light in the instrument panel flashed, showing it was engaged.
The wheel still spun. I then rolled forward and tried again, but the same thing happened. I then got out and locked the front hubs, and selected low-range on the gear selector. The bakkie then reversed without a problem. Could my diff-lock be broken, or did it not engage?
IAN SHAW – By email
Having the front hubs locked all the time should not make much of a difference to fuel consumption. Many people drive like this all the time without damaging the hubs.
On Hilux 4x4s made from 1998 to 2004, the diff-lock can be engaged only in low-range 4×4 mode. According to Toyota, this is a safety measure, because driving with a diff-lock engaged on a hard surface, or at high speed, can damage some of the transmission components, especially during cornering when the wheels would fight each other because the rear wheels are forced to rotate at the same speed.
However, a sensible driver would find that there are some situations in which one would prefer to select the diff-lock in high-range four- or even two-wheel drive. The wiring modification to make this possible can be found from a number of Internet sources.