QuestionQUESTION: Hello, I have a 1996 Dodge Stratus with a 2.5L V-6 engine and automatic transmission. The other day I was driving down the rode and coming to a stop when I noticed the speedometer drop to zero before I had come to a complete stop. I turned on to the next road and as I did I noticed the transmission was in limp mode (second gear) and the speedometer was not reading. No Check Engine Light (CEL) had come on at this point. I was only 2 miles from my house so I turned around and drove it back home. Still no CEL so I decided to go around the block and see if I could get the CEL to come on. Sure enough it did. I went back home and hooked up the code reader. It read a P500 (no vehicle speed sensed) and a P715, I think that was the number anyway (No output speed sensed. So I went to the auto parts store and bought an input and output speed sensor, figured I would change them both while I was in there. I replaced both sensors and still the car was in limp mode. After further investigation I found that the wires to the output speed sensor had shorted/broke. They had rubbed the transmission lines. I have since fixed the wires by cutting them, splicing them back together and soldering and heat shrink wrapping them each individually. I am now getting a P1698 code (no buss link) and the car is still in limp mode. What could the output speed sensor wires shorting/breaking have taken out to cause a P1698 code that I am getting? Thanks.
ANSWER: Hi Gary,
The CCD buss wires between the tcm and the bcm are presumably the problem. There are a twisted pair of wires from pins 4 and 43 at the tcm to pins 14 and 6, respectively of the 14-pin black plug (note that there is an adjacent 12-pin black plug) at the bcm under the dash that is connected to the rear side of the fuse box and has 4 multi-pin plugs. So the starting point would be to verify those wires are patent and also shake the harness to verify.
I am uncertain if the speed sensor issue caused this, or perhaps the repair process.
Roland
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QUESTION: Roland, Well I tore into this thing some more today. I pulled the PCM and TCM mainly so I could get part numbers off of them if needed and so I could get a better look at the harness down by the speed sensors and like I said what I found that caused the original problem was the two wires that go to the output speed sensor were rubbed through on the transmission lines that go up to the radiator. This car has 278,699 miles on it so stuff like this is expected I guess. I would imagine that what ever wire had voltage on it going to the output speed sensor must have shorted out. It took out the TCM. The way I figured this out was I took a gamble. I went on car-part.com and looked to see if a near by salvage yard had a TCM. One about 15 miles from me had one for $40 with the same part number as mine. I went and got it, stuck it in and problem resolved. The guy at the salvage yard even said if it does not fix my problem, bring it back and he will give me my money back. I guess it was not such a big gamble but it worked out for me. Thanks for your help. Gary.
ANSWER: Hi Gary,
Thanks for the progress report and solution. I hope that resolves it. I wonder about your theory because the sensors generate their own voltage signal so there is no supply voltage on either wire of the speed sensor. But, you are doing very well to get that sort of mileage on thss etax transmission.
Roland
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QUESTION: Roland, That is interesting that the sensors generate their own voltage signal and there is no supply voltage on either wire of the speed sensors. The only other possibility is that maybe a voltage spike took out the TCM. I had unhooked and hooked up the battery a thousand times, well maybe not quite one thousand times ;), taking stuff in and out of the car to get to the speed sensors etc. Who knows. I have drove it 60 miles already and so far so good. Thanks again. Gary.
AnswerHi Gary,
I could be wrong but when one wire says 'sensor ground', and the other wire says 'sensor signal', then to me that implies that there is little or no voltage applied to the signal wire by the TCM. It may be a few volts and the circuit could be looking for current flow pulses generated by the sensor, but in any case I don't picture the shorting of the signal wire to be able to blow the TCM. So we'll keep our fingers crossed....
Roland
