Overdrive Question

nalley4

Test Drive
Ok I just bought a second Xterra, a 2005 S 4.0 2wd. My question is when driving I have to keep the OD off or she will keep downshifting and upshifting. Plus tach reads higher than when I turn OD off. I’m getting better gas mileage with it off. Is this normal in the second gens or what? Previous owner stated it had been checked out by multiple transmission mechanics and can find nothing wrong/or a reason for it doing this.
 

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Brunnie

Bumpers Installed
Supporting Member
Location
Colorado Springs
Ok I just bought a second Xterra, a 2005 S 4.0 2wd. My question is when driving I have to keep the OD off or she will keep downshifting and upshifting. Plus tach reads higher than when I turn OD off. I’m getting better gas mileage with it off. Is this normal in the second gens or what? Previous owner stated it had been checked out by multiple transmission mechanics and can find nothing wrong/or a reason for it doing this.

First of all, when OD is turned off you are in 4th gear so naturally the engine will run faster (tach will read higher) than if it is 5th gear (OD).
Secondly, if your transmission is hunting between 4th and 5th, you're right at the point where the computer senses that you are in the wrong gear, lugging the engine so it downshifts. In that respect it is normal. Maybe the question that needs asking is... at what speed is this shifting occurring?
 

nalley4

Test Drive
First of all, when OD is turned off you are in 4th gear so naturally the engine will run faster (tach will read higher) than if it is 5th gear (OD).
Secondly, if your transmission is hunting between 4th and 5th, you're right at the point where the computer senses that you are in the wrong gear, lugging the engine so it downshifts. In that respect it is normal. Maybe the question that needs asking is... at what speed is this shifting occurring?
I am running lower RPMs with OD off.
With OD on it doesn’t seem to matter what speed I’m running. 55-60, if my speed slows down any, it will downshift with OD on. When speed moves up, it up shifts. It’s a constant thing because no one can hold a single speed. With OD off tach hangs anywhere from 22-2500 rpms. If I turn OD on, she jumps to 3000-3200. Hope this helps any confusion
 

Brunnie

Bumpers Installed
Supporting Member
Location
Colorado Springs
I am running lower RPMs with OD off.
With OD on it doesn’t seem to matter what speed I’m running. 55-60, if my speed slows down any, it will downshift with OD on. When speed moves up, it up shifts. It’s a constant thing because no one can hold a single speed. With OD off tach hangs anywhere from 22-2500 rpms. If I turn OD on, she jumps to 3000-3200. Hope this helps any confusion

When you say OD "on"... is the light on the dash illuminated?

In 5th gear, OD on (dash light not illuminated), 22-2500 at 60-65 mph is the sweetspot, and normal rpm range.
At that speed, turning OD off (dash light illuminated) the rpms should jump up to about 3000 rpms.
 
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Brunnie

Bumpers Installed
Supporting Member
Location
Colorado Springs
From the Owner's Manual:
Overdrive switch
Each time your vehicle is started, the transmission is automatically “reset” to overdrive ON.
ON: With the engine running and the shift selector in the D (Drive) position, the transmission upshifts into Overdrive as vehicle speed increases.

Overdrive does not engage until the engine has reached operating temperature.


OFF: For driving up and down long slopes where engine braking is necessary push the Overdrive switch once. The O/D OFF indicator light in the instrument panel comes on at this time.

When cruising at a low speed or climbing a gentle slope, you may feel uncomfortable shift shocks as the transmission shifts into and out of Overdrive repeatedly. In this case, depress the Overdrive switch to turn the Overdrive off. The O/D OFF indicator light in the instrument panel comes on at this time.

When driving conditions change, depress the Overdrive switch to turn the Overdrive on.

Remember not to drive at high speeds for extended periods of time with the Overdrive off.
This reduces fuel economy.
 

nalley4

Test Drive
When my light is illuminated is says OD off.
I know this all sounds weird but does as stated in other post. With my OD off/light illuminated, I have lower rpms than when OD is on/light NOT illuminated. Even at operating temp, any reduction in speed she will downshift. Any increase in speed she will up shift(with OD on/light not illuminated. With OD off/light is illuminated and gear indicator is in 4, I get lower rpms and better gas mileage
 

nalley4

Test Drive
I will try to post a video tomorrow to clear any confusion as to what I am describing. It acts as though it is reversed. Weird as everything I said sounds, that is exactly what it is doing. Multiple mechanics( so I’m told) were unable to find anything amiss or have any idea as to why it does this. Even a road test and no answers.
 

Brunnie

Bumpers Installed
Supporting Member
Location
Colorado Springs
It acts as though it is reversed. Weird as everything I said sounds, that is exactly what it is doing. Multiple mechanics( so I’m told) were unable to find anything amiss or have any idea as to why it does this. Even a road test and no answers.

IMHO... something is reversed and I seriously doubt that "multiple mechanics" looked at it. If that (multiple mechanics) is true I'd be at the dealership and letting them look at it. Something is definitely amiss.
 

TerryD

Total Tease
Supporting Member
Location
Covington, Va
Could be slipping in 5th not allowing the TCC to lock up. But that should set a DTC IIRC.

Checked you fluid level? Hot, engine running, cycle through the gears, put in park and check.
 

nalley4

Test Drive
It was at the Nissan dealership and they couldn’t find anything or explain it. By multiple, there were 3. I have all service records since the previous owner bought it. And he owned it a number of years and stated it has done that ever since he bought it. I have warmed it, cycled the gears, checked fluid, she just had filter and fluid changed. It doesn’t seem to be hurting anything. So ass backwards we’ll be.
 

nalley4

Test Drive
Could be slipping in 5th not allowing the TCC to lock up. But that should set a DTC IIRC.

Checked you fluid level? Hot, engine running, cycle through the gears, put in park and check.
My check engine light is on. I’ve only had this X less than a week. I haven’t had the opportunity to run a scan on it. But do know it has a O2 fault because there were 2 new cats put on and didn’t replace the 02 sensors at that time(again I have the service records. I’ll get her scanned and see if any codes show.
 

TerryD

Total Tease
Supporting Member
Location
Covington, Va
Lead with the check engine light next time please. MOST faults in the 2nd Gen will show up there and should be taken seriously.
 

nalley4

Test Drive
I didn’t lead with the check engine light because there is no code for anything with the issue. I tried posting a video but will not let me upload. Going to try some Lucas transmission anti slip and see if that helps.
 

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nalley4

Test Drive
Ok I got a bit of an update. I erased the codes and cleared the check engine light. Driving with OD on she was not downshifting and up shifting but the rpms were at the 3500 range. I don’t know what the heater control bank 1 sensor 2 fault even means but the other is O2 sensor. I guess time will tell about the shifting. Still want to add the Lucas and see if that helps.
 

nalley4

Test Drive
Are you bypassed? If not What color is your trans fluid and what color is your radiator fluid ?

nalley4Test Drive
New
Bypassed? I don’t know.
Previous owner had transmission serviced at the dealership. As well as reversing the radiator and transmission lines. This was done less than 1 yr ago. It’s reddish. Not the strawberry color thank goodness. Radiator fluid is good. He stated that this issue has been going on since he bought the Xterra some years back.
 
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nalley4

Test Drive
Those codes are both of your downstream O2 sensors. HO2S = Heated O2 Sensor. They're not terribly hard to change. The harness plugs are the worst. Buy NTK as I think they are the OE supplier.

24244 and 24247:

https://www.rockauto.com/en/catalog...67,exhaust+&+emission,oxygen+(o2)+sensor,5132

Does it do anything else weird like leaving the tail lights on after you shut the engine off?
I haven’t checked the tail lights, but I will today. Thanks for the info on the sensors. I got new ones but haven’t had time to change them yet.
 

nalley4

Test Drive
I haven’t checked the tail lights, but I will today. Thanks for the info on the sensors. I got new ones but haven’t had time to change them yet.
The codes for mine were P0037 and P0430. P0430 is my 02 sensor, the other is heater control something
 

TerryD

Total Tease
Supporting Member
Location
Covington, Va
I haven’t checked the tail lights, but I will today. Thanks for the info on the sensors. I got new ones but haven’t had time to change them yet.

The tail lights being on after key-off is an indicator you're having issues with the IPDM which is involved in many of your systems. Not a fool proof thing, because it's sometimes hard for a computer to tell if it's lost its mind.
 

nalley4

Test Drive
The tail lights being on after key-off is an indicator you're having issues with the IPDM which is involved in many of your systems. Not a fool proof thing, because it's sometimes hard for a computer to tell if it's lost its mind.
Nothing wrong with the tail lights. But on the way into work this morning, the check engine light returned. And so did the up shifting and downshifting. Codes are the same as before. Need to replace ASAP but can’t believe that would cause the reversed OD/shifting issues
 

Zack.

Has been dubbed Arnold
Supporting Member
Location
Livermore, CA
For the emissions codes there’s something where they aren’t fully cleared when you clear with an odb2 tool. Unhook the negative cable from the battery while you are changing the downstream 02 sensors - the 30 minutes or so it’s not connected should wipe the codes.
 
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