Need Code 23 Help
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Need Code 23 Help
My 85 is having trouble idling when cold. I did a scan and found a Code 23 (Manifold Air Temperture Signal Voltage High). The ECM will not go into closed loop. Does the Code 23 prevent the ECM from going closed?
I'll be testing the harness to the MAT for correct voltage from the ECM but unfortunately the MAT sensor is on the bottom side of my Super Ram plenum. Testing the sensor resistance in place could prove to be a challenge.
I'll be testing the harness to the MAT for correct voltage from the ECM but unfortunately the MAT sensor is on the bottom side of my Super Ram plenum. Testing the sensor resistance in place could prove to be a challenge.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
http://forums.corvetteforum.com/1582020529-post7.html
If you disconnect the harness end you should easily be able to put a DVM on the wires to the MAT
http://www.chevythunder.com/mat_code_23.htm
Le Mans Master
Joined: Feb 2005
Posts: 6,479
Likes: 565
From: Clearwater Florida
......... On the early MAF controlled TPI motors , the ONLY function of the MAT is to help control the EGR ... the MAF sensor by design includes intake air temp in its feedback to the ECM ... so a malfunction in the MAT circuit would not affect idle quality but will set the CEL ....... code 23 is usually caused by an open circuit ( sensor not plugged in ) ... as mentioned there is a two-wire weatherpack connector to the drivers side of the rear of the engine near the oil pressure sender ... but , with a SR it may be near impossible to see let alone touch .........
