1995 Grand Caravan SE has an intermittent check engine light.

I did the key code trick, and ended up with errors 27 and 34. I'm having trouble deciphering what they actually refer to.

34 relates to the cruise control, which make sense because that crapped out a while ago.

27 is a little more mysterious. Can eliminate anything to do with the immobilizer right off the bat as it doesn't have one. The van runs kind of rough when the light is on. Is there a "more common" cause of this code as opposed to the others?

Seems it can be any ones of these beauties (pulled from https://dodgeforum.com/forum/dodge-r...ll-list.html):

P1251 Air Mixture Solenoid Circuit Malfunction
P1252 Pedal Correlation PDS1 and LPDS High
P1253 Pedal Correlation PDS1 and LPDS Low
P1254 Pedal Correlation PDS2 and LPDS High
P1255 Pedal Correlation PDS2 and LPDS Low
P1256 Pedal Correlation PDS1 and HPDS
P1257 Pedal Correlation PDS2 and HPDS
P1258 Pedal Correlation PDS1 and PDS2
P1259 Immobilizer to PCM Signal Error
P1260 THEFT Detected, Vehicle Immobilzed
P1261 Cylinder #1 High To Low Side Short
P1262 Cylinder #2 High To Low Side Short
P1263 Cylinder #3 High To Low Side Short
P1264 Cylinder #4 High To Low Side Short
P1265 Cylinder #5 High To Low Side Short
P1266 Cylinder #6 High To Low Side Short
P1267 Cylinder #7 High To Low Side Short
P1268 Cylinder #8 High To Low Side Short
P1269 Immobilizer Code Not Programmed
P1270 Engine RPM Or Speed Limiter Reached
P1271 Cylinder #1 High To Low Side Open
P1272 Cylinder #2 High To Low Side Open
P1273 Cylinder #3 High To Low Side Open
P1274 Cylinder #4 High To Low Side Open
P1275 Cylinder #5 High To Low Side Open
P1276 Cylinder #6 High To Low Side Open
P1277 Cylinder #7 High To Low Side Open
P1278 Cylinder #8 High To Low Side Open
P1280 Injection Control Pressure Out Of Range Low
P1281 Injection Control Pressure Out Of Range High
P1282 Excessive Injection Control Pressure
P1283 IPR Circuit Failure
P1284 Aborted KOER - ICP Failure
P1285 Cylinder head over temp sensed

 

You have a OBD1 vehicle, so all those "P" codes do not apply as those are OBD2 codes.

OBD1 code 27 is an injector problem. This could be any number of things, a bad injector, broken wire, or a loose or corroded connector. I'd start by checking the connections to all the injectors. Make sure there's no crud in the connector and that it's making good contact.

 

If the connections look good you can use a noid light to test signal from the PCM. Can be signed out from some parts stores.

 

88 display used for start or test(will only be seen using a DRB2 scanner)
11 crankshaft signal or ignition signal, no reference signal during cranking
12 memory to controller has been cleared within 50-100 engine starts
13 map sensor vacuum, no change from start to run or output voltage does not equal throttle position
14 map voltage too high or too low
15 vehicle speed sensor, no signal detected
16 loss of battery voltage sense
17 low engine temperature, possible thermostat fault
21 oxygen sensor signal, neither rich or lean detected or O2 shorted to voltage
21 knock sensor circuit(starting in 89)
22 coolant temp sensor voltage low/high
23 air charge temp sensor voltage high/low detected
24 throttle position sensor voltage high/low
25 automatic idle speed motor driver circuit, short or open detected
26 injectors 1,2,3 peak current not reached, problem in injector control circuits cylinder 1 and/or 2.
27 injector control circuit does not respond to control signal, problem in injector control circuits 3 and/or 4
31 purge solenoid circuit, open or short detected
32 egr solenoid circuit, open or short detected
33 a/c clutch relay circuit, open or short detected
34 speed control servo solenoid, open or short detected
35 radiator fan control relay circuit, open or short detected
36 wastegate solenoid, open or short detected
37 Baro read solenoid
37 PTU solenoid circuit(starting in 89)
41 charging system circuit not responding to control signal, alternator field circuit not switching properly
42 fuel pump or auto shutdown (ASD) relay voltage sensed at controller
42 Z1 voltage sense
43 ignition control circuit not responding
44 battery temperature voltage circuit problem
45 turbo boost limit exceeded-map sensor detects overboost
46 battery voltage too high..overcharging
47 battery voltage too low...battery voltage low or charging output low
51 air/fuel at limit
51 lean exhaust indication, O2 voltage latched below .450 volts
52 rich exhaust indication, O2 voltage latched above .450 volts
53 internal controller failure (normal code on a re-calibrated controller)
54 fuel sync signal not detected during cranking
55 end of message
61 baro read solenoid, open or short detected
62 emr mileage not stored
63 eeprom write denied
64 flex fuel sensor signal out of range
64 VNT solenoid #1 circuit
65 manifold tuning valve, open or short detected
65 VNT solenoid #2 circuit
66 no ccd messages
67 VNT "A" side failure
76 ballast bypass relay, open or short detected
77 speed control relay, open or short detected

Our vans are OBD1, the codes you listed have nothing to do with our vehicles.

 

I figured those P codes were the comparable OBD2 codes because of the way they were separated in the original list. Those were all under "27". But I did find the actual code beforehand and thought maybe those would help clear it up.

At any rate, the problem crops up when it's humid or has been raining, so there's probably a fray or exposed something or other that shouldn't be. I don't drive the van any more myself, but my brother and dad have been.

We'll see what we can discover with some investigation. Thanks.

 

Go through and clean/grease all the underhood connections. I've had intermittent CELs, Misfires, rough running, etc all be caused by just poor connections.
Just cleaning/greasing may solve your problem, or you may find the real issue in the process.