Dodge Repair: service engine soon alarm set


Question
QUESTION: 1999 Dodge Grand Caravan 3.3L 4speed 195K

It has happened three times since yesterday. While driving, both Service Engine Soon and Alarm Set lights come on; the van takes a jerk (kind of missing, I believe it loses power for a fraction of a second) and then with in a couple of seconds, every thing is fine again. Out of three times, I was driving at 50 mph and once at 20 mph.

ANSWER: Hi Shafique,
The service engine soon light suggests that an engine fault happened and set a fault code number in the memory of the engine controller. To get the fault code turn the ignition key:" on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window see if the mileage reading is replaced by a 4-digit number preceded by a P. If so let me know the number. If not, then it might be that the ignition switch jiggled out of the 'run' position momentarily or the switch might have a flaky section. But check now for fault codes.
By alarm set light I assume that you mean the vehicle theft security system is activated light. That can happen if a power door lock is activated which sets up the vtss but I can't understand why that should happen while driving unless one of the doors appeared to be 'open' which in effect means "ajar". You might try pushing outward on each of the doors from inseide the vehicle while you are in motion above 15 mph to see if that provokes the door locks to click. If so, then that door is probably not firmly secured in the door frame. So you would move the door striker mounted in the door frame a few millimeters inward so as more tightly secure the door in question in the door frame.
Please read the PS (below) and respond to it.
Thanks,
Roland

---------- FOLLOW-UP ----------

QUESTION: My guess is that, since both lights come on and go off at the same time, it must be a single event that is causing it. Is there any other condition, under which both lights will come on at the same time?

Do the fault codes stay in system even though the warning lights are off now?
The on-off-on-off-on sequence does not work in my van. I must visit a shop to get the codes, so I want to be sure that those are still there.

However, I am inclined to go with your first diagnoses of ignition switch as after these many years, I am now able to take out the key without pressing it a bit! In addition, the Alarm Set will also come on if a key other than the fab key (or I believe equally no key) is used. A jiggling key will indicate both lights. I am thinking of using the key alone (with the weight of key chain and other keys) to see if it makes a difference.

Thanks again!

Answer
A code is stored for quite a while, but from what you describe it sounds to me like an issue with the ignition switch. So try the idea about the weight on the key. The check engine light, if it truly is reporting a fault will usually remain "on" also, depending upon the severity of the problem.
Roland