Hello to all. I have a 97 Grand Caravan that is doing very weird things. Sometimes, while going down the road, the check engine light comes on, sometimes it stays off. Occasionally, ALL the instrument lights come on and all the guages (including speedometer) go to zero. The funny thing is that the van keeps running fine with all the lights on and the guages off. The bad thing is that once I shut it off, it won't start again until several hours later. It then starts and either acts normal or the check engine light comes back on. It usually takes a few days before the guages and lights freak out again. The transmission was recently rebuilt, and these problems started about that time, but the mechanic can't figure it out. It doesn't spit out any codes. For some reason he replaced the O2 sensor, but it didn't fix the problem. I'm wondering if it could be related to the speed sensor since the speedometer goes away, but wouldn't that cause the van to die? If it is the speed sensor, can anyone tell me where it is and what tools I need to replace it. Frankly, I don't want the mechanic working on it anymore. I wonder if it is a flakey connection to some module since it is intermittant. I don't want to replace the computer without trying less expensive possibilities first. Thanks in advance.

 

i dont think the speed sensor would cause your entire panel to short circuit. Most likely theres an exposed wire next to the computer or sensor and on those days when theres humidity any kind of fluid (transmission fluid?) would be causing problems. That would explain why the problem only happens occasionally. Make sure you dont have any leaks, secure all wire connections. Im sure others will have more suggestions.

 

Check all the grounds. There are several ground eyelets that would have been taken off for the trans work. Make sure they are all connected and TIGHT. A loose ground is worse than an unconnected one, as they are much more difficult to track down from the symptoms. I'd start there. Mike

 

Thanks for the replies. I have a little more info now. The problem happened again the other day while my sister was driving the van. She hit the top of the dash softly (she says) and the problem went away. I did the reset/trip test and got no codes. I then tried the keyswitch test and got a 12 - 66 - 66 - 55. I think the code 66 means that the PCM was not talking to the BCM or TCM. Might be the cluster, since the problem went away by hitting the top of the dash. Of all these, which ones would cause it not to start until several hours of sitting before it would start? Does anyone know where the BCM is located? I heard somewhere under the Dash. I heard the TCM is on the firewall and the PCM might be under the battery. Any help would be appreciated.

 

I have very similar problems, and also found hitting dash sometimes helped! I think it is also related to warm envirmonment in the dash area!