QuestionVehicle Has Been Downshifting Erratically / Dies At Idle
My 1994 Dodge Grand Caravan 3.8 FWD +200,000 miles has been having strange tranny issues for about 6 months now. Took it to one mechanic and he said it needed a new solenoid pack. Put in a rebuilt solenoid pack. This cure lasted a few weeks.
Had some starting issues. Did some more research and found that the TPS may be bad…replaced TPS. Starting and fuel economy improved greatly. However, tranny probs continued to occur on a very infrequent basis.
For awhile, the vehicle has gone into "limp mode.” Read the flash codes, indicate problem with speed sensor. Replaced both speed sensors.
Last couple of week’s noticed that tranny seemed to shutter when making hard right hand turns. Yesterday, the tranny stayed in gear until RPM hit 3K (right after this first 3 grand tranny shift, the check engine light came on and has stayed on) and then it shifts. Car also dies when I bring it to a full stop.
Did the flash codes and they say a code 24. Thought that the newer TPS might be bad, checked voltage at center pin and it seemed to stay right at 4.6 d.c. volts both at idle throttle setting as well as at full throttle. According to the info I found on the internet it indicated that idle position voltage should be around 1 volt.
Put in new TPS; no change in drivability. Pulled battery cables to clear codes, once again “Check Engine Light” was on and has stayed on; plus no change in drivability.
Found info on web about how to do a quick test of ECM. Went into the drivers side upper cab area, put my analog multi-meter set on impedance at the top right and bottom left ---- my harness only had 8 pins---pins. Motion swept from left to right but did not bounce or return. Per internet source this indicates a bad ECM.
To me all of the above sounds like some sort of electrical/electronic problem, but am stumped as to how to troubleshoot further.
Suggestions Appreciated!
PoorPaul
AnswerHi Paul,
On the transmission, I would suggest doing a code readout of the blue data link connector under the dash near the steering column as that one reads the transmission (while the one under the hood reads the engine) controller. That plug socket is 6-pin, three on a side, and is different in shape from the one under hood. So check with the shop that is going to do the readout to be sure they have that rectangular-shaped plug or they won't be able to do the readout. The dieing of the engine when coming to a stop is indicative of the torque converter lock up not releasing as it should. The hard right turning issue makes me wonder about a loose plug or maybe a wire with compromised insulation that is rubbing on a metal ground surface due to the positional shifting of the harness/powertrain due to the angular acceleration/deceration of the turn.
I followed everything else but the last 3 paragraphs. What codes are stored at present? Can you explain where these 8 pins are located, and what color wires were on those pins that you measured? And what was the theory about it testing the ecm?
On the tps measurements, the middle pin should vary its resistance as compared to either side pin as you move the throttle (this measured with the plug removed), and the voltage on that center pin should vary (with the plug inserted) when compared to either side wire (one side should have 4.6V the other should be ground potential.
So please let me know the details.
You can respond via the "thank/rate" tab below using the comments section. That way you don't have to wait for me to be available to take a follow-up question.
Thanks
Roland
