FJ80 Test Drive - Center Diff Lock Question (1 Viewer)

[LS1FJ40]

The front and rear lockers should lock regardless if the CDL is engaged or not. And yes the CDL should lock when put in Low

No. The front and rear lockers require a signal from the center diff lock in order to engage.

 

[jonheld]

No sir, it did not have a center diff button. Did US market trucks ever come with a center diff lock button for 4Hi? I thought those were all retro-fitted.

1991/1992 FJ80s came with CDL dash buttons in US spec.
In factory configuration, all US spec 80s should lock the center diff when shifted into low range on the transfer case. However there are 2 ways that the previous owner might have disabled this. The easiest is to remove a connector on the transfer case, the other is with the "PIN 7 MOD" which is more involved. Both would require a CDL dash switch in order to lock the center diff both in high range and in low range.

Or the center diff actuator is skeshaad.

 

[LS1FJ40]

"PIN 7 MOD"

NOT TO BE CONFUSED WITH THE “7 PIN MOD”.

But it does make for interesting comments from Jon when someone asks about the “7 PIN MOD”.

 

[jonheld]

NOT TO BE CONFUSED WITH THE “7 PIN MOD”.

But it does make for interesting comments from Jon when someone asks about the “7 PIN MOD”.

Oh no you didn't...

 

[surfpig]

NOT TO BE CONFUSED WITH THE “7 PIN MOD”.

But it does make for interesting comments from Jon when someone asks about the “7 PIN MOD”.

Is that like the 7/10 pin split mod?

 

[LS1FJ40]

Oh no you didn't...

Sure did!! Merry Christmas to me!!

 

[LS1FJ40]

Is that like the 7/10 pin split mod?

Similar. The 7 pin mod is a wussies version. Made famous by the French.

 

[Will Van]

1991/1992 FJ80s came with CDL dash buttons in US spec.
In factory configuration, all US spec 80s should lock the center diff when shifted into low range on the transfer case. However there are 2 ways that the previous owner might have disabled this. The easiest is to remove a connector on the transfer case, the other is with the "PIN 7 MOD" which is more involved. Both would require a CDL dash switch in order to lock the center diff both in high range and in low range.

Or the center diff actuator is skeshaad.

Thanks for the info! That's very helpful. There is no way the seller pulled the connector from the transfer case or did the Pin 7 Mod. He didn't even know how to put it in 4 low or how to check the oil. I think the actuator was just gummed up from non-use.

On a separate note, is there an easy way to tell if an FJ80 has a full float rear axle? If the truck has front and rear lockers, it has a full float rear axle, right? Also, if it has rear disc brakes and ABS, it has a full float rear axle? Did any FJ80s come with rear disc brakes and not a full float rear? Did any FJ80s come with FR and RR lockers, and not a full float rear?

Obviously the easiest way to tell is to pull the rear wheel cap and look at the hub. I'm just trying to get my ducks in a row while I do my FJ80 shopping. A lot of times the seller doesn't really know what he has, so if you know what to look for, you can get a deal.

For example, you could ask the seller, "Does the truck have four wheel disc brakes?," which seems like a reasonable question. And you wouldn't tip your hat that you're actually wondering if the truck has a full float rear axle.

(Again, not my truck. Just an example of a full float axle/hub)

 

[jonheld]

On a separate note, is there an easy way to tell if an FJ80 has a full float rear axle?

Easiest thing to do is look at the rear diff. If there's a bolt on rear cover it's a semi floater. If there's no cover it's a full floater. In the US market, 91 and 92 FJ80s were semi float, rear drums, no lockers. 93+ FZJ80 almost all were FF rear with disks, but I did see a 95 with semi floater and drum rears. However it's country of origin was unknown at the time.

 

[Will Van]

Easiest thing to do is look at the rear diff. If there's a bolt on rear cover it's a semi floater. If there's no cover it's a full floater. In the US market, 91 and 92 FJ80s were semi float, rear drums, no lockers. 93+ FZJ80 almost all were FF rear with disks, but I did see a 95 with semi floater and drum rears. However it's country of origin was unknown at the time.

Pics of the rear diff cover and bolt for semi-float?

 

[LS1FJ40]

If it has lockers it has full float.

 

[gummycarbs]

Obviously the easiest way to tell is to pull the rear wheel cap and look at the hub. I'm just trying to get my ducks in a row while I do my FJ80 shopping. A lot of times the seller doesn't really know what he has, so if you know what to look for, you can get a deal.

For example, you could ask the seller, "Does the truck have four wheel disc brakes?," which seems like a reasonable question. And you wouldn't tip your hat that you're actually wondering if the truck has a full float rear axle.

There's no point in focusing on that for getting a deal. 91 & 92 are FJ80 have the 3FE engine, a CDL button, and rear drums. 93 - 97 are FZJ80 with the 1FZ-FE engine, no CDL button stock (the transfer case has a viscous coupling in it, and the CDL switch can be added), and full-floating axles with four-wheel disc ABS.

The only tricky 'deal' is to look for a diff lock rotating switch to the left of the steering wheel. But good luck with that. Every goober on Craigslist thinks that a CDL button adds $2k to the value, because they have no idea that every rig has a locking center diff and only needs the button added.

Also, chances are extremely high that the sensors will be corroded and the lights won't come on. There's a good chance the actuator will be corroded, too. If you want triple locked, look for the door code and verify the correct axles are still in place (i.e. learn what the locker actuator looks like). Chances are it won't engage without some cleaning and repeated attempts.

 

[Will Van]

There's no point in focusing on that for getting a deal. 91 & 92 are FJ80 have the 3FE engine, a CDL button, and rear drums. 93 - 97 are FZJ80 with the 1FZ-FE engine, no CDL button stock (the transfer case has a viscous coupling in it, and the CDL switch can be added), and full-floating axles with four-wheel disc ABS.

The only tricky 'deal' is to look for a diff lock rotating switch to the left of the steering wheel. But good luck with that. Every goober on Craigslist thinks that a CDL button adds $2k to the value, because they have no idea that every rig has a locking center diff and only needs the button added.

Also, chances are extremely high that the sensors will be corroded and the lights won't come on. There's a good chance the actuator will be corroded, too. If you want triple locked, look for the door code and verify the correct axles are still in place (i.e. learn what the locker actuator looks like). Chances are it won't engage without some cleaning and repeated attempts.

Apologies. Maybe looking for a "deal" was the wrong description. I just want to be armed with as much knowledge as possible. The purpose of the original post was to confirm that: (1) I was actually engaging the 4 low properly; (2) When 4 low is enabled, a light should illuminate on the dash that indicates the CDL is engaged; (3) the FR and RR lockers will not engage without the CDL engaged.

I should have also mentioned, I know what the FR and RR actuators look like on the diffs, and I climbed under the truck to confirm they were actually in place (and the seller didn't just add a locker switch to the dash and claim it was 3X locked). I was mainly concerned about engaging the lockers, not determining if the truck actually had lockers.

I agree, the sensors and actuator were probably corroded, which prevented the CDL from engaging and the dash light from illuminating.

Thanks for the info on the 93 - 97 FJZ80 series with full-floating axles and four-wheel disc ABS.

 

[cruiserdan]

93 - 97 are FZJ80 with the 1FZ-FE engine, no CDL button stock (the transfer case has a viscous coupling in it, and the CDL switch can be added), and full-floating axles with four-wheel disc ABS.

Not accurate. For 1993-94 ABS, disc brakes and a rear FF axle were optional. The vast majority were built this way but some semi-float drum brake tucks did make it over here. They also came fitted with a CDL switch. Beginning with the 1995 model year ABS, FFA and disc brakes were standard equipment for US models.

 

[LS1FJ40]

Not accurate. For 1993-94 ABS, disc brakes and a rear FF axle were optional. The vast majority were built this way but some semi-float drum brake tucks did make it over here. They also came fitted with a CDL switch. Beginning with the 1995 model year ABS, FFA and disc brakes were standard equipment for US models.

No lockers in 93-94 if it has semi float and rear drums though, correct Dan? Only lockers with full float and discs.

 

[jonheld]

If it has lockers it has full float.

Yes, but not all FF were locked. The OP asked how to tell if the rear was a FF. In this case, the easiest thing to do is simply look at the rear diff.

 

[jonheld]

Sorry, but none of these pictures are very good. However on a FF rear, the rear cover is welded to the housing and cannot be removed.

On a SF rear there are 10 studs/nuts that hold the rear inspection cover in place. It's very apparent.

 

[Will Van]

Thanks for all of the info guys!!!

Just to make sure I have it all straight:

• All 3x locked trucks have a full-float rear axle
• All four-wheel disc brake trucks have a full-float rear axle
• All rear drum brake trucks have a semi-float rear axle***
  
• Some 93 - 94 trucks had the optional full-float rear axle, ABS, and four-wheel disc brakes, but did not have FR and RR lockers
• If the truck has a bolt-on rear diff cover, it's a semi-float.
• If the truck has a welded-on rear diff cover, it's a full-float
• If the truck has a rear hub body behind the wheel cap, it's a full-float

***Some non-US spec Cruisers came with rear drum brakes and a full-float rear axle.

Did I get that correct?

 

[cruiserdan]

I do not recall ever seeing an 80 with a full float drum brake axle. 40,60,70, yes.