How do I find the error causing the check engine light to go on?

Asked by May 06, 2017 at 08:11 PM about the 1991 Dodge RAM 150 2 Dr S Standard Cab LB

Question type: Shopping & Pricing

7 Answers


Find someone with a scanner that can read OBD1 trouble codes.

1 people found this helpful.

Some auto models provide an owner a method of reading trouble codes without the need of special equipment. Does anybody know if my Dodge Ram has this capability?


Just turn the key on-off-on-off-on, not to the start position, but to the run position. Then be ready to count the flashes of the check engine light. The check engine light will flash five times in a row, then a pause, then five times again. Then, it will flash another number of times, and pause, then another number. Example: It flashes 5 times, pauses, 5 times, pauses, that's a 55, which is the normal start of the cycle. Then it might flash eight times, pause, and flash seven times. That's a code 87. They will all be two digit codes. Once it flashes 55 again, it's run it's course, and will repeat.

Best Answer Mark helpful

Here is a video on this...

3 people found this helpful.

Great. This is the answer I was looking for. I will give this a try tomorrow. Thanks!


Your welcome.

The results of my testing worked as described above except for the initial 55 code. My results, which I verified a second time, returned a 12 code followed by a 55 code. The 12 code was expected since I had disconnected the battery recently. Again, I want to thank Rowefast for the helpful and speedy response.

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