QuestionQUESTION: My 95 Cirrus stays in limp mode most of the time. Sometimes only the tach works in the instrument cluster, sometimes none of the gauges work or I get a “no bus” message on the gear selector. Sometimes all of the gears are selected. but lately it seems only the speedometer does not work. Sometimes the speedo works and sometimes all gauges work and the car shifts normally. Sometime the speedo works but the car still will not shift. For a while before the limp mode started I noticed the car down shifted kind of hard when I would come to a stop. The trans fluid was just at the add mark so I added trans fluid atf4 from the dealer. No change.
I have followed the advice below you gave to Dave at one point. He had the same code 66 error on his 95 cirrus 2.5L as mine. Maybe a side issue but my running lights cut out when I pull the emergency brake or sometimes cut out randomly when driving Except the ABS light is always on.
There is continuity between pins 4 and 43 at the tcm plug and14 and 6, respectively of the black plug at the BCM. When I check the voltage at 4 and 43 of the TCM it returns 0 for a split second then says 1, then says ALT in a little black box beside the numerical readout. My multimeter does not test for alt current. Am I doing the reading wrong? I attached the neg lead of the meter to ground and the positive one to the terminals. Then I did it the other way around but got the same readings.
The car has a 16 hole black plug under the dash but I can only see seven slots that look like they are actually active. So do I assume it is an OBDII. I can’t see a readout plug under the hood.
I pulled and reseated most of the plugs to theBCM. I also unscrewed and cleaned all of the grounds I could see under the hood. They were not corroded.
Just the fact that it works perfectly sometimes makes me think there is a short or a poor ground. I doubt the transmission is bad.
If I unplug the TCM and start the car it behaves exactly the same as when plugged in including the running lights going off when I pull the E brake. I obviously need some help.
This leaves me wondering if my BCM is not working.
“The tcm is on the opposite side of the fuse box from the pcm. The 66 code says that the ccd bus messages from the tcm are not being seen on the network. You could check pins 4 and 43 at the tcm plug to see that they are continuous to pins 14 and 6, respecively of the black plug at the bcm located at the underdash fuse block(back side thereof). Or easier would be to check that there is bias voltage of -2.5v on 4 and +2.5 on 43 pins of the tcm. Try flexing the harness to check for interminttent connections. If that all checks out, then suspect that the tcm is bad.
The pins of the plug itself should show the voltage, so just count the pins and measure them with the ignition in the 'run' position. The bcm provides this voltage to the plug so you should be able to see it without having it plugged in. The colors are white/dark green and violet/brown,
Roland”
ANSWER: Hi Herman,
Yes, the black multi-pin plug under the dash is for an OBD-II reader. Rather than guess based upon the symptoms, it is better to take advantage of the self-diagnostic capability built in to the engine and transmission controllers.
Get a free readout for the 4-digit fault code numbers, using the under-dash black plug, at an Autozone parts store (or for about $40 at an independent shop) and ask what they mean, what they suggest, and approximate cost. Then write back and we'll consider the codes in light of the symptoms to see what to do next.
You also can get engine (but not transmission) fault codes using the ignition switch (OBD-I codes by this means). Turn the key: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light to begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to be sure of an accurate count. Tell me those flash counts in the order of appearance.
Chances are we'll get some ideas from those readouts.
Roland
---------- FOLLOW-UP ----------
QUESTION: Here are the codes I got from a shop that had an OBDll scanner.
SCAN PCM FOR CODES 08 MAR 10 09
CODES:
66 NO BODY CCD MESSAGE FROM BCM
66 NO EATX CCD MEASSAGE FROM TCM
He said there were no error codes stored in the TCM.
He also said if the modules themselves are shot they are not going to tell you. Hmmmm.
On the way home everything worked fine. Then as I was slowing down and almost stopped it seemed to shift a bit hard. I don’t know if it was because of the downshifting or because it went into limp mode just at that particular time. After that it stayed in limp mode even though the speedometer still worked. A while later the speedometer would go off and on.
Does one need to flash a BCM from a different car?
Do I just have a poor ground somewhere or what do I try next?
ANSWER: Revised Answer-
Hi Herman,
I have to ponder on this history. My '95 manual suggest that the code could mean a problem with either the TCM or the BCM,without distinguishing which. Why do you think the BCM is involved?
The problem is with the transmission so I would suspect the TCM if I suspected anything.
I will get back to you with a revised answer when I have had time to think it over.
Roland
---------- FOLLOW-UP ----------
QUESTION: I initially got a double 66 reading when I did the key turn code reading. The shop got a double 66 reading also. I had not told them what I got before hand. I then told them this was not what I was looking for and that I wanted the readouts or stored codes from the TCM. They said there were none but tried again with no results. The reason I think the BCM is a problem is that
1: Their scanner said 66 NO BODY CCD MESSAGE FROM BCM
2: When I check the voltage at 4 and 43 of the TCM it returns 0 for a split second then says 1, then says ALT in a little black box beside the numerical readout. My multimeter does not test for alt current. Am I doing the reading wrong? I attached the neg lead of the meter to ground and the positive one to the terminals. Then I did it the other way around but got the same readings.
As I said in the first part of the message I could not seem to get voltage from the BCM. Unless I did the readings wrong.
AnswerHi Herman,
Do you have a manual for your meter? It may explain what 'alt' means. Maybe it is detecting the pulses associated with the digital signals and ALT stands for 'alternating'? Because the trans is the problem, I would be inclined to try to find an identical TCM from a wreck of the same car/engine for '95 or maybe '96 if it had identical part number. If the wires I described are connected, then it points toward the TCM being bad, and the 66 supports that.
Roland
PS:One suggestion that came from my '95 Sebring manual with the same engine/transmission as yours is to go back to the fellow with a reader. Erase the codes. Then disconnect the PCM and try the reader again. See if the code 66 comes back. If it doesn't then that would implicate the PCM as the cause. If the code 66 is still present with the PCM disconnected then replace the TCM. That is the conclusion to draw, provided that the connections on the pcm and tcm plugs are all patent which you could check out if you want to spend the time doing it.
