Code 48 - Stepper Motor -IACV - Land Rovers Only

UsedBlue · 08-30-2008, 07:16 AM

Hello- our Disco I 1994 auto had the transfer case replaced almost 2 yrs ago and ever since we got it back the Speedo doesn't work and she kept stalling anytime we made a sudden stop or came off the highway- or even when we were making a slow turn on the road (which gets dangerous when you're in the middle of the intersection and stall when the cars are coming at you!)- so we changed the TPS throttle position sensor, changed the vacuum hoses which had cracks and then we put 2 different stepper motors in it. One stepper was brand new from the Astro van that was recommended on this website which looks to be the same part- and then when that didn't stop the 48 code from popping up again on the OBD we bought a USED OEM part and put that in. It stopped stalling as much, but the code 48 is still on the OBD and the engine light is still on and it stalls less now, but it still stalls and the code is still on the OBD and the check engine light is still on. Would it make sense to spend the money on a brand new one- or is there something else that we're missing?
Can anyone give an idea? I would hate to blow more money on this stepper and buy a new one- but if it's recommended we will. They are about $185 versus the used one I got for $20! The astro van one was about $40 brand new.
Thanks to anyone that can lend some advice

Dutchgit · 08-30-2008, 11:23 AM

If the speedo doesn't work I would say that that is the problem. The Road Speed Transducer tells the engine management if the car is moving or not by giving pulses to the speedo and the ECU (engine management) It could simply be the case that after the work was done on the gearbox, they didn't re-connect the RST.
You'll find the connection most likely on the LH chassis rail next to the main gearbox or there abouts if remember correctly.
If the RST doesn't work it doesn't raise the revs slightly to prevent stalling when you pull away or come to a stop.

bartell · 08-30-2008, 01:49 PM

Quote:

Originally Posted by Dutchgit

If the speedo doesn't work I would say that that is the problem. The Road Speed Transducer tells the engine management if the car is moving or not by giving pulses to the speedo and the ECU (engine management) It could simply be the case that after the work was done on the gearbox, they didn't re-connect the RST.
You'll find the connection most likely on the LH chassis rail next to the main gearbox or there abouts if remember correctly.
If the RST doesn't work it doesn't raise the revs slightly to prevent stalling when you pull away or come to a stop.

Good diagnosis.

The ECU uses the transducer signal to determine whether the car is moving and if so, it disengages the idle speed control mode. If the transducer is defective, poorly earthed or unconnected the idle speed control becomes erratic.

James

UsedBlue · 08-30-2008, 02:35 PM

Thank you-
we have heard that before- but then another couple of people said that the older Disco Models- the Disco I's weren't that technical and on the II's were the only ones that had the speed sensor that was connected to the ECU and dealt with the management and did exactly what you both said in your replies. Plus, why wouldn't the speed sensor code be popping up on the OBD instead of the 48 Stepper Motor?
So we actually went out and bought another speed transducer about a year ago for about $110, and we got some tool advice from another website and bought the tools and tried to install it- we couldn't see what we were doing and we heard a slight 'crack uh oh' noise. We thought it cracked the housing- but we will need to pull it and try again.
We diconn. the battery etc etc and nothing changed- the speedo didn't work. We still have the new speed sensor installed and we still have the old one. Actually a couple of months ago- after I got off the highway- the speedo did actually work until I came to a stop. It was almost like the air pressure was lost on it- not that it makes sense- but the needle was slow moving and wasn't working right- but at least it worked for a few mins. Then it never worked again. So what does THAT mean? it isn't hooked up right or the part is bad? Someone said there was another part that may not be connected right.
So do we buy a 3rd speed sensor? or is there a way to tell if the 'new' one is working....?
Thanks again !

08-30-2008, 07:16 AM	#1 (permalink)
UsedBlue Member Join Date: Apr 2007 Posts: 84 Gallery: 0	Code 48 - Stepper Motor -IACV Hello- our Disco I 1994 auto had the transfer case replaced almost 2 yrs ago and ever since we got it back the Speedo doesn't work and she kept stalling anytime we made a sudden stop or came off the highway- or even when we were making a slow turn on the road (which gets dangerous when you're in the middle of the intersection and stall when the cars are coming at you!)- so we changed the TPS throttle position sensor, changed the vacuum hoses which had cracks and then we put 2 different stepper motors in it. One stepper was brand new from the Astro van that was recommended on this website which looks to be the same part- and then when that didn't stop the 48 code from popping up again on the OBD we bought a USED OEM part and put that in. It stopped stalling as much, but the code 48 is still on the OBD and the engine light is still on and it stalls less now, but it still stalls and the code is still on the OBD and the check engine light is still on. Would it make sense to spend the money on a brand new one- or is there something else that we're missing? Can anyone give an idea? I would hate to blow more money on this stepper and buy a new one- but if it's recommended we will. They are about $185 versus the used one I got for $20! The astro van one was about $40 brand new. Thanks to anyone that can lend some advice

08-30-2008, 11:23 AM	#2 (permalink)
Dutchgit Senior Member Join Date: Aug 2008 Location: Germany Posts: 102 Gallery: 0	If the speedo doesn't work I would say that that is the problem. The Road Speed Transducer tells the engine management if the car is moving or not by giving pulses to the speedo and the ECU (engine management) It could simply be the case that after the work was done on the gearbox, they didn't re-connect the RST. You'll find the connection most likely on the LH chassis rail next to the main gearbox or there abouts if remember correctly. If the RST doesn't work it doesn't raise the revs slightly to prevent stalling when you pull away or come to a stop. __________________ Nothing is sure but death and taxes.

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08-30-2008, 02:35 PM	#4 (permalink)
UsedBlue Member Join Date: Apr 2007 Posts: 84 Gallery: 0	Thank you- we have heard that before- but then another couple of people said that the older Disco Models- the Disco I's weren't that technical and on the II's were the only ones that had the speed sensor that was connected to the ECU and dealt with the management and did exactly what you both said in your replies. Plus, why wouldn't the speed sensor code be popping up on the OBD instead of the 48 Stepper Motor? So we actually went out and bought another speed transducer about a year ago for about $110, and we got some tool advice from another website and bought the tools and tried to install it- we couldn't see what we were doing and we heard a slight 'crack uh oh' noise. We thought it cracked the housing- but we will need to pull it and try again. We diconn. the battery etc etc and nothing changed- the speedo didn't work. We still have the new speed sensor installed and we still have the old one. Actually a couple of months ago- after I got off the highway- the speedo did actually work until I came to a stop. It was almost like the air pressure was lost on it- not that it makes sense- but the needle was slow moving and wasn't working right- but at least it worked for a few mins. Then it never worked again. So what does THAT mean? it isn't hooked up right or the part is bad? Someone said there was another part that may not be connected right. So do we buy a 3rd speed sensor? or is there a way to tell if the 'new' one is working....? Thanks again !

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