QuestionQUESTION: Van is a 1996 T&C with 3.3L engine.
I believe that I have 2 unrelated problems:
1) The gauges stopped working. They came on about once a week for a few seconds. The overhead display works on Direction and and Temperature but all other overhead displays have "dashes" instead of data when the gauges are off. When the gauges are on, the overhead console works fine. I have checked the solder joints on the instrument cluster and all of the connector pins are OK when tested with an ohmmeter. All of the plug wires to the instrument cluster are good for voltage and continuity except that I have not checked the 2 CCD bus wires. I have checked the connections on the plug to the instrument cluster and there is voltage on B+ (pin 2) and Ignition (pin 11). The ground (pin 7) is good. The panel lamp connections (voltage on pin 6 and ground on pin 13) are good and the panel lamps work. No other lights or the odometer light up. The overhead console diagnostics result in "PASS". Since there are no instrument cluster lamps, there is no "Check Engine" light and I cannot check the codes with the MIL. I have attached a OBDII Scanner to the Data Link Plug and the result is "PASS no codes returned". Until the last week, this problem did not affect starting and operating.
I want to determine if the instrument cluster itself is bad or if there are issues with the CCD bus.
a) If the plug to the cluster is connected with the CCD bus connections removed (pins 9 & 10 on the instrument cluster) should the odometer or any other warning lights light up?
b) Does the overhead console get its information from the instrument cluster or does it come from other modules?
2) Now the van won't start. The engine turns over and "coughs" once but then just cranks. If I turn off the key and back on again, the engine "coughs" once again. I was told that the instrument cluster can affect starting, and was told to disconnect the instrument cluster plug. The engine does the same thing with the instrument cluster plug disconnected.
I have checked that there is 12 volts constantly on the B+ at the coil pack during cranking. The other three leads at the coil pack do have pulses on the grounds when disconnected from the coil pack but no pulses if I read the wires when connected to the coil pack. Both the primary and secondary resistance at the coil pack are correct. I have replaced the coil pack. I have verified that there is 8 volts on the orange wire to the crank and cam position sensors. The other 2 leads on both the crank and cam position sensors change from about .3 to 5 volts, depending on the position of the engine crank and cam shafts. The fuel injectors are getting pulses, the fuel pump is working and the fuel pressure is just under 50 pounds at the Schrader valve.
Again, I have scanned for codes with a OBDII scanner and there are no codes.
Any suggestions?
Thanks.
ANSWER: Hi Tom,
The warning lights on the cluster are all based on info from the CCD bus as are the odometer/speedometer/gauges.
The overhead cluster is on the data bus which is a fully shared system on a single 'tree' of spliced-on components. It is 'centered' in the body control module so you might want to be sure that all the fuses to that are OK (1,2,3,6, in the box under the dash, and 19,22,28 in the box under the hood), The CCD bus wires should each show a DC voltage of either +2.5 or -2.5v.
The fuse assignments are based on the '98 manual which is the closest I have, unless the '95 is applicable (let me know and I can give you the equivalent fuse numbers from that mnanual).
On the start problem, it might be related to the failed cluster, but not if it persists even when unplugged. One possibilitiy to check is whether your exhaust gas recirculation valve (egr) might be sticking in the slightly ajar position which leans out the mixture too much to start and maintain the idle. It has a velve stme inside a flange located between the body of the valve and vacuum top part, and there is a slot in the stem that allows you to move it back and forth and to close via internal spring-action. It should close to a dead stop under spring action. It if seems sticky in its action spray some WD-40 on the valve stem whete it enters the body of the valve and work it back and forth to free it up.
Roland
PS:Please 'rate' my answer, and where you see the question about a 'nomination for volunteer of the month' consider giving me a 'yes' response. I'm tied for the lead at this point.
---------- FOLLOW-UP ----------
QUESTION: Thank you for the information. As far as the no start issue, I checked the EGR valve as suggested and everything is good. Your answer to the first question may have guided me to the problem for the no start.
The power and grounds to the data link connector test out correctly. However, the CCD + and - (pins 3 and 11) do not have the +2.5 or -2.5v that was in your answer. The CCD+ (pin 3) has 11.1 volts and the CCD- (pin 11) has 0.5 volts. I assume that the CCD bus is not working correctly and could also result in the no start condition. I see my next step to be to disconnect each module connected to the CCD bus and see if I can locate the module causing the incorrect voltage readings. The modules that I see connected to the CCD bus are PCM, BCM, TCM, Overhead Console, Controller-Anti-Lock Brakes, Radio, Airbag Control Module, Instrument Cluster, and Data Link Connector. I do not believe that there is a Sentry Key Immobilizer Module on this model. The instrument cluster is already disconnected. Does this seem to be the right track? Where does the + or - 2.5 volts originate? Is it in one module (the PCM?) or is it a combination of several modules (PCM, BCM, TCM)?
AnswerHi Tom,
It looks to me as though the body control module is where the bias voltages for the CCD bus are generated. So look for the violet/brown and white/black wires which are probably on pins 3 and 34 of the black plug (ref.'98 manual) of 7 and 20 of the blue plug (ref.'95 manual). I doubt that the radio is part of the bus in a '96, but the rest of the modules you listed are fair game. Please let me know what you learn from the 'exercise'.
Roland
PS Please 'rate' my answer, and where you see the question about a nomination for me to be 'volunteer of the month' consider answering with a 'yes' as I am in a close race for the recognition at this moment, and it ends tomorrow afternoon.
