D1 wont shift into overdrive
#21
#28
Honestly you need to start from square 1 and go back to basic troubleshooting: Quadruple-check engine grounds. What's the manifold vacuum (warm)? Maf voltage? Engine Temp (use an infrared temp gun to verify). Ohm out the temp sensor/s. TPS voltage. Are there one or two temp sensors? (I honestly don't know on the Gem's). Does the brake switch work properly (that would kick off the OD). Alt properly charging and Batt good? Is the odometer working properly? Any connectors or wires corroded or damaged? Tranny cable adjustment set right? Is there a switch for the high/low range which is still partially engaged or shorted? (Many vehicles disable OD in low range). Any particular fuses associated with the tranny? I'm speaking in general terms for modern EFI 4x4', some of these may not specifically pertain to the Disco 1, but I'd check them all and not rule any out just now. Write down the readings you capture. Are they well within the proper range per the Rave manual? Try resetting the computer.
I say "WELL" within the range, bc I've personally had a MAF on a VW that was at the bottom end of the 'normal' range (but a little) and the car totally ran like crap. No CEL codes. Took forever to zero in on that ...till I finally ruled everything out one by one, then broke down and spent the $60 for a new MAF. Yeah, the MAF voltage via the scanner was definitely higher with the new sensor, instantly ran great. I've also had temp sensors which had drifted and also caused shifting and engine operational problems. I'm not saying it's your MAF or temp sensor, but the point is there are a variety of factors that can cause your tranny to not engage OD. Don't skip some w/o checking.
You should rule all that basic stuff out first before condemning the tranny. Always start with the simple things, then work to the more complex (tranny). 80% of the time it's the simple things. You've already done the fluid. If you had a real good scanner, you could observe a lot of these reading and make short work of it (still check the engine temp with a separate temp gun). Or get one of the new crop of relatively inexpensive scanners that give ya real-time information. But nearly all of the sensors that matter in this case can be read on a multi-meter in a few minutes anyway by backprobing with wires. You might want to pick up an inexpensive vacuum gauge.
I say "WELL" within the range, bc I've personally had a MAF on a VW that was at the bottom end of the 'normal' range (but a little) and the car totally ran like crap. No CEL codes. Took forever to zero in on that ...till I finally ruled everything out one by one, then broke down and spent the $60 for a new MAF. Yeah, the MAF voltage via the scanner was definitely higher with the new sensor, instantly ran great. I've also had temp sensors which had drifted and also caused shifting and engine operational problems. I'm not saying it's your MAF or temp sensor, but the point is there are a variety of factors that can cause your tranny to not engage OD. Don't skip some w/o checking.
You should rule all that basic stuff out first before condemning the tranny. Always start with the simple things, then work to the more complex (tranny). 80% of the time it's the simple things. You've already done the fluid. If you had a real good scanner, you could observe a lot of these reading and make short work of it (still check the engine temp with a separate temp gun). Or get one of the new crop of relatively inexpensive scanners that give ya real-time information. But nearly all of the sensors that matter in this case can be read on a multi-meter in a few minutes anyway by backprobing with wires. You might want to pick up an inexpensive vacuum gauge.
Last edited by Mark G; 11-15-2021 at 12:37 AM.
#30
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