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A little reading,,,,
D5 KOEO DIAGNOSTIC TROUBLE CODE (DTC) P0237
- DTC P0237 indicates turbo boost sensor A circuit low input.
- Possible causes:
- MAP signal circuit open, shorted to ground, shorted to B+ , or shorted to VREF
- open or shorted VREF circuit
- open or shorted signal return circuit
- damaged MAP sensor
- damaged PCM
- Key off.
- Disconnect MAP sensor connector.
- Connect the MAP sensor tester between the vehicle harness connector and the MAP sensor.
- Insert the MAP sensor tester banana plugs into a digital multimeter. Note: Green light on tester indicates VREF is OK (4.5-5.5 volts) and signal return is OK. Red light indicates VREF is either too low or too high. No lights indicate VREF or signal return are open or shorted.
- Key on.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">GO to D6 . </TD><TD width="50%">Red light "less than 4V" on or no lights, GO to D11 . Red light "greater than 6V" on, GO to D14 . </TD></TR></TBODY></TABLE>
D6 MAP SIGNAL SHORT TO GROUND CHECK
- Disconnect PCM, inspect for damaged or pushed-out pins, corrosion and loose wires. Service as necessary.
- Install breakout box. Leave PCM disconnected.
- Disconnect MAP sensor harness connector.
- Measure resistance between Pin 34 (49 State except Econoline) or Pin 88 (California and all Econoline) and Pins 25, 51, 76, 77, 91, 103.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">GO to D7 . </TD><TD width="50%">REPAIR short to ground or signal return in MAP signal Circuit 358 (LG/BK). CLEAR DTCs and RETEST. </TD></TR></TBODY></TABLE>
D7 MAP SIGNAL SHORT TO VOLTAGE CHECK
- PCM disconnected.
- MAP sensor connector disconnected.
- Key on/engine off.
- Measure resistance between Pin 34 (49 State except Econoline) or Pin 88 (California and all Econoline) and Pins 55, 71 and 97 at the breakout box.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">GO to D8 . </TD><TD width="50%">REPAIR short to power in MAP signal Circuit 358 (LG/BK) and REPLACE MAP sensor. CLEAR DTCs and RETEST. </TD></TR></TBODY></TABLE>
D8 MAP SIGNAL SHORT TO VREF CHECK
- PCM disconnected.
- MAP sensor connector disconnected.
- Key off.
- Measure resistance between Pin 34 (49 State except Econoline) or Pin 88 (California and all Econoline) and Pin 90 at the breakout box.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">GO to D9 . </TD><TD width="50%">REPAIR short to VREF in MAP signal Circuit 358 (LG/BK). CLEAR DTCs and RETEST. </TD></TR></TBODY></TABLE>
D9 MAP SIGNAL CONTINUITY CHECK
- PCM disconnected.
- MAP sensor connector disconnected.
- Measure resistance between Pin 34 (49 State except Econoline) or Pin 88 (California and all Econoline) at breakout box and Circuit 358 (LG/BK) at the MAP harness connector.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">GO to D10 . </TD><TD width="50%">REPAIR open MAP signal Circuit 358 (LG/BK). CLEAR DTCs and RETEST. </TD></TR></TBODY></TABLE>
D10 PCM CHECK
- Connect PCM to breakout box.
- MAP sensor connector disconnected.
- Key on.
- Measure voltage on MAP signal Circuit 358 (LG/BK) at MAP harness connector.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">REPLACE MAP sensor. CLEAR DTCs and RETEST. </TD><TD width="50%">REPLACE PCM. CLEAR DTCs and RETEST. </TD></TR></TBODY></TABLE>
D11 VREF VOLTAGE CHECK
- Disconnect MAP sensor tester connector from MAP sensor, leaving it connected to vehicle harness.
- Key on/engine off.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">REPLACE MAP sensor. CLEAR DTCs and RETEST. </TD><TD width="50%">GO to D12 . </TD></TR></TBODY></TABLE>
D12 VREF CONTINUITY CHECK
- Key off.
- Disconnect PCM, inspect for damaged or pushed-out pins, corrosion and loose wires. Service as necessary.
- Install breakout box. Leave PCM disconnected.
- Disconnect MAP sensor tester from vehicle harness.
- Measure resistance between Pin 90 at breakout box and VREF Circuit 351 (BR/W) at MAP sensor connector.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">GO to D13 . </TD><TD width="50%">REPAIR open in VREF Circuit 351 (BR/W) between PCM and MAP sensor. </TD></TR></TBODY></TABLE>
D13 SIGNAL RETURN CONTINUITY CHECK
- PCM disconnected.
- Measure resistance between Pin 34 (49 State except Econoline) or Pin 88 (California and all Econoline) on breakout box and signal return Circuit 359 (GY/R) at MAP sensor connector.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">REPLACE PCM. CLEAR DTCs and RETEST. </TD><TD width="50%">REPAIR open in signal return Circuit 359 (GY/R). </TD></TR></TBODY></TABLE>
D14 VREF SHORT TO B+ CHECK
- Disconnect PCM, inspect for damaged or pushed-out pins, corrosion and loose wires. Service as necessary.
- Install breakout box. Leave PCM disconnected.
- Key on.
- Measure voltage between Pin 90 and ground.
<TABLE cellSpacing=0 cellPadding=3 width="92%" border=1><TBODY><TR><TH width="50%">Yes </TH><TH width="50%">No </TH></TR><TR><TD width="50%">REPLACE PCM. CLEAR DTCs and RETEST. </TD><TD width="50%">REPAIR short to B+ in VREF circuit. CLEAR DTCs and RETEST. </TD></TR></TBODY></TABLE>




