Hi Everyone

I had the Service Engine Soon light come on about a year ago right after I did my 33" modification and at first thought it might have been because of a pulled wire somewhere. I plugged the vehicle into an OBD II code reader at work (I work at a major automobile dealer for German cars) and found "P" Code 1875 that Translated to: Valve for Torque Support mount short circut to ground. Witch told me absolutely nothing. So I found a cross reference website for Suzuki codes and it turns out the code translates to 4wd Low switch circut malfunction.

So I wasn't to scared of that and figured I would change the 4wd low switch once I got around to it. I finally made a grate buy recently in purchasing a used AT and transfercase that are fully functional from a vehicle that was running with no warning lights on in the dash for about $90. I swapped both switches on the transfercase (my 4WD light was always on as well) and I got rid of the 4WD light. That light works correctly now. I again plugged the vehicle to a computer and erased the P1875 code and drove for about 5 min. no light, I was very happy with my repair. But then at lunch time I drove it again and the Service engine soon came back on! I check the code and sure enough P1875 came up again. The switch I put in is used I know, but was working in the previous vehicle. Does anyone out there know if this code can com from something else? I did go over the wiring and as far as I can tell there are no pulled wires or other obvious damage.

Oh, I have had the vehicles speedometer correctly calibrated at an authorized shop for such work so I could get my vehicle inspected. It would not pass Icelandic inspections without a correct speedometer. I have seen some comments about a Vehicle speed sensor/sender perhaps being a culprit of this kind of code, this is why I stated the speedo information. Any and all help are appreciated.

Best regards,
Tryggvi

I cant believe no one has responded to this yet. The only thing I can think of is the mount or bung for the sensor is causing the problem. If your motor/trans/tcase are moving around as they're prone to do when your workin' it, is it possible the housing is hitting something?

Do you have front hub lockouts? or is your truck a shift on the fly?

Wild

Hi Everyone

Thanks for your input so far.

 Bentparts - There is allot of clearance for the little sensors/bung especially since I have a 2" body lift. Plus I have triple checked they are torqued down, not loose and correctly connected. The 4WD Low is a black connector and the 4WD (green light in dash) is white. Getting to the sensors from inside the vehicle through the floor where the transfer case stick is was not hard at all. I took a short drive with everything open through the floor and there was no abnormal movement I could see and no clearance issues. The T/C mounts seem do be fine. Off topic, I did notice a slight 1/2" tear in the T/C stick boot on the T/C itself, vary minor but I repaired it with aircraft grade silicone (my dad is an aviation mechanic).

Wildgoody - I have manual front hubs that look like original Suzuki parts with Lock/Free positions and work well. Those would not be called shift on the fly would they? Last year I disassembled them and fully cleaned and re lubricated so they work grate in all wheather with minimal effort to lock/unlock and they do keep put where they are supposed to be in each end position. I have crawled under the vehicle with the hubs locked and unlocked to check rotation of the CV axle shafts and everything seems to work just fine.

Some new information: I visited the one and only local Suzuki dealer and spoke to the most knowledgeable person there (an automechanic for Suzuki for many years as well as for Ford vehicles). I asked him if there is any possibility that the P1875 code can come from something other than a defective 4WD Low range sensor. His first question to me was: are you running larger than stock tires? So then and there I got were he was coming from and told him yes 33" tires and further more asked him if this might be in regards to a VSS (vehicle speed sensor) issue? He went out back and looked it up and said yes. If there is a discrepancy of (I don't recall if it was percent or KPH) of 10% or 10 KPH that this could trigger the P1875 / Service Engine Soon light. I asked if the dealer would be willing to rectify this problem for me and he told me they do not have equipment to do so and would shy away from any modifications other than making a correct repair as Suzuki would have done originally, which is impossible on such a modified vehicle.

I checked up on my friend who's father owns the speedometer calibration shop I went to about a year ago to have my speedometer calibrated and asked him for help on this issue. After some discussion he suggested a "Tru Speed Calibrator", can be found at "http://www.speedcalibrator.com/". I am not sure this is what I need and am wondering if anyone out there knows about this part and if it might help me correct my problem? I am aware that messing with the ECM is slightly dangerous if done incorrectly and might destroy it. Purchasing a new one would cost me astronomical amounts here in Iceland! I saw on a 4x4 forum (when Goggling this item) that it should be an easy install. There should be 3 wires out of my Automatic transmission (Ground, Power and signal wire) correct me if I am wrong. And that I splice this unit into the signal wire. Any information on these wires, colors, potential problems, the calibrator or anything else is appreciated.

Best regards,
Tryggvi

I have no experience with that device, but I'm glad you found the cause of your problem. With your knowledge and skills I wouldn't be afraid to try the re-calibrater. Let us know how it works.

I was thinking that if your truck came with no lockout hubs, that it has the
vacuum controlled front diff, and it might be setting off the p1875  Check
Engine light.

If your truck has a VSS does it also have a speedometer cable? or is it
electric wire driven?

Still thinking

Wild

Hi

I am pretty sure that my vehicle was equipped with the manual locking hubs from the factory but I can not say that with 100% certainty since I was not the original owner.

My vehicle has a mechanical speedometer cable from the T/C all the way up to the dashboard and onto the back of the actual speedometer. The cable has a correction device (gear drive) to correct the speedometer. This unit is mandatory if I want to be able to drive on public roads and since this is my only vehicle and daily driver, I had to have the speedometer calibrated. I do wonder though if the change the calibrator is making is actually making this fault appear because of the discrepancy of output speed from the Automatic transmission via electrical signal and the gear driven speedometer calibrated cable? This was one of the thoughts me and my friend at the calibration shop were wondering about. This also coinsides with the thoughts of the technician at the Suzuki dealer.

I have asked around at work about this Tru Speed box and the Mitsubishi division has used it on highly modified Pajeros running 38" - 44" (Montero in the USA) with no problems. I am seriously looking into this option. It costs $220 though witch is pretty steep in my opinion. And I still do not have 100% confirmation that this actually WILL correct my problem, yet it seems to be looking highly likely at the moment.

Best regards,
Tryggvi

Have you disconnected the 4XLow switch?  This switch grounds the signal, which tells the ECM that the transmission is in low gear.  Disconnect it and see if CEL/code comes back (after clearing it).   If it comes back with switch disconnected I would check for a crimped wire to ground, or it may be that the ECM is comparing the output shaft speed sensor (inside transmission) with the VSS and determining that the difference means that you are in low range, assuming the switch is bad (by not indicating low range).
The Tru Speed box is used to change/calibrate electronic speedometers (and yours is a cable drive unit with an electronic VSS head for the ECM).  So in theory you could recalibrate the signal from Speedometer VSS signal to the ECM, but it would be trial and error to get it indicate what the ECM would accept as correct for the Output Shaft Speed Sensor.
 

Disconnect the speedometer correction box and see if it goes away, if
I were having that problem I would just use the box to pass your
inspection and use a GPS for your speed the rest of the time

Wild

Really, get it past inspection and buy yourself a nice Garman Handheld GPS withTopo maps for the price of that calibrater!

My vehicle has a mechanical speedometer cable from the T/C all the way up to the dashboard and onto the back of the actual speedometer. The cable has a correction device (gear drive) to correct the speedometer. This unit is mandatory if I want to be able to drive on public roads and since this is my only vehicle and daily driver, I had to have the speedometer calibrated. I do wonder though if the change the calibrator is making is actually making this fault appear because of the discrepancy of output speed from the Automatic transmission via electrical signal and the gear driven speedometer calibrated cable? This was one of the thoughts me and my friend at the calibration shop were wondering about. This also coinsides with the thoughts of the technician at the Suzuki dealer.
Tryggvi

I think that is correct the VSS for the ECU will be in the speedo head so the ECU will be comparing the corrected speed from the VSS with the uncorrected speed from the AT. There are a number of different speedo corrector boxes around that may work with the A/T, you would have to contact the manufacturers.

I think that is correct the VSS for the ECU will be in the speedo head so the ECU will be comparing the corrected speed from the VSS with the uncorrected speed from the AT. There are a number of different speedo corrector boxes around that may work with the A/T, you would have to contact the manufacturers.

I know this post is almost 10 years old but did anything ever come of it??  I'm having the same issue with my 98 Sport with P245 tires and a 13% difference.  Getting the exact same P1875 codes.