Transmission ailments - 1999 Range Rover 4.0
Background; 4 months ago front driveshaft universal goes at 70mph. Takes out wiring harness, O2 sensor, shift sector, holes the floor, bashes the trans pan, cable bent,..... Car is delivered to shop, insurance approves the "subsequent damage". We pay deduct and drive shaft. Long wait for parts. Car is thought to be done but last check by shop finds that it is not down shifting to first at all times and throws fault. Decide to replace crankshaft sensor. Seems to fix. Pick up car (2 months?). Flips trans fault (gearbox fault) on dash. Seems to reset after rest but then will do it again. Return car to shop, check codes now replace input shaft sensor. This has it! NO. Test drive / fault. Now the output shaft sensor. That does not get it. Shop calls and says they are done, can't fix, get it out. Insurance is still on board at this point. They cover tow to dealer & diagnostics. Think it is the bent cable and re-adjustment to the selecter switch. Come test drive! No! trans fault. Back to dealer - More time, more diagnostics,no solutions. Dealer final answer - replace the trans. - insurance says "time out".
When the car is not in fault mode it seems to drive fine. I have contacted ZF trans/tech in Chicago. The fault codes are#27 output speed sensor, no signal present, fault present and intermittant / # 43 - 4th gear ratio incorrect, fault not currently present. ZF feels this is most likely electrical, possibly as simple as a loose wire from the output sensor to the ECU.They feel that withoutsolving the 27 code first the 43 code is a symtom of an incorrect read.
So - does anyone have any insight into this! Where is the trans ECU located? electrical diagram? Have good volt/amp meter and can check but do not want to fry the ECU.

 

A failing MAF will cause a 4th. gear out of ratio issue. Just a possible idea.

 

Mike - Thanks- What is the MAF? I see you seem to be the answer man for many of these posts. What is your opinion on what ZF thinks about the 4th gear possibly being a misread, or that the fact that the 27 code is intermittant and may well be a bad or loose connection? It seems possible that when they replaced the damaged harness that something is not quite right. The car never had any trans problems prior, and now it seems like just throwing parts at various code readouts which may have only been symtoms of the real problem.

 

Fault code 27 is the hard fault. code 43 is probably related to the output sensor fault. I am guessing that when you hit higher speeds and the trans goes to shift into 4th gear, the fault is set and now you are stuck is 3rd gear (limp home) untill the ignition is recycled. this is due to the output sensor.Did anyone check the continuity for the circuit? ZF trans are fairly bulletproof, but by your description of the damadge caused internal damadge could have occured.

 

MAF is the sensor on your air intake hose between the air filter and the t/body.

 

Yesterday topped trans with 1/2+ qt. ZF tech has told me that these are varly senative to fluid level? To early to tell if this willl help. In regards to the symtoms; The first indication that something has happened is after driving and stopping, when taking off it will seems to be in 2nd gear. It then upshifts, and seems to be at correct rev at speed. But will no longer kick down shift on acceleration, the sport mode will not come on, and it continues to not go to 1st. So it is not set in 3rd , if that is what "limp mode" is. You mentioned the continuity, which is what ZF seems to suspect as well as the code is intermittent. I have not checked the wiring, nor has the dealer. I am ready to do this myself as I am very frustrated with getting this resolved. I need to get a wiringdiagram and locate the control (ECU?). Is a factory manual the way to go or isthis info avalible?
To Disco Mike - How does the air intake come into play, and wouldn't this throw it's own code fault?

 

If I'm correct the fault codes started after the damge occurred. I would start checking the wiring in that area (connections,seperations, etc..) then branch out from there.

 

Thanks to all for your input. I am wondering if anyone has a suggestion for the best way to check the wiring from the transmission computer to the sensors. Is the factory manual thebest source for a diagram?Were is thetrans/ECU located? In regards to the MAF possibly having some affect on my troubles; Is there a test/diagnosic to determine it's condition? Previously we had converted to coil over suspension (kit from Atlantic Brit.) all was well prior to damage. Now I have the dash lights on the level indicator are all litand also the indicator on the instrument cluster indicates vehicle arrow up. This system had a bypass module to keep the car from thinking it had a fault. It is working in this respect, except for these lights. Any thoughts? Thanks

 

Wow I feel your pain! seems to be all going wrong at once!! The tcm (trans cntrl module) is located under the drivers seat. I would check the wiring from this location back to the round connector @ the transmission. there are three wires to checkin regardsto the output sensor. pink, yellow, and a shieled wire (usually a wire with a copper colored wrap around it) as for the air susp conversion, I have the same kit on my 97. the override module as supplied by atlantic brit is tied into the becm, located under the pass side front seat. check there first to ensure it is still hooked up correctly.

 

Unfortunatly I do not have the time right now to give this the attention that it needs, and I am in disbelief that the dealer(s) are so limited in their knowledge or that LR has made it a policy to only go so far and then take the "black box" route. "We checked all we can - put in a new trans". How many people have been talked into this to the tune of $4000-$5000!!! that may not have been needed. To the wiring! Is there a way to check continuity from the leads you mentioned at the TCM as they connect? (Should there be a continuity say from the the pink back through the sensor back to another lead?) I understand the sensor picks up magnetic pulses from a notched ring on the output shaft, but I am not clear if the sensor at rest is an open or closed switch. If open then you could only check the path from the TCM to the sensor, which would eliminate any voltage loss in a given wire , but not the unit itself (which was replaced??). Any problems with the TCM itself? I will check the wiring at the suspension module (have copy of install instructions, though AB was not very helpfull when called) may have to locate who makes this for them for some tech help.